Plastics: Establishing The
Path To Zero Waste
A pragmatic approach to sustainable management of
plastic materials
Teresa Clark
Abstract:
Plastic items are a critical part of modern society and they are used in almost every aspect of our lives. One
of the values of plastics for packaging and manufacturing articles is the strength and durability of the
material, however, after use this durability means that the plastics remain after use and continue to
accumulate in the environment indefinitely. This means that as we use more and more plastic, we will also
discard an ever growing amount of plastic that will last for centuries.
Today, plastics are disposed of in several ways including recycling, landfilling, incineration, composting and
littering. In the US, recycling captures approximately 9% of plastics, we incinerate (burn) nearly 1% and we
litter or compost less than a fraction of a percent. This leaves nearly 90% of plastic being discarded into
landfills. Sustainability managers must be able to identify the most sustainable method for handling plastics
after use.
To be truly sustainable, we must understand what is the most environmentally and economically beneficial
thing to do with plastic and embrace methods that will address the 90+ percent of plastic discarded in the
landfill each year. Only by addressing these issues can we maximize our success in reducing plastic waste by
creating value in the process; a system known as “Zero Waste”.
Plastics: Establishing The Path to Zero Waste
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Plastics: Establishing The Path to Zero Waste
Copyright © 2015
All rights reserved. This book or any portion thereof may not be reproduced or used in any manner
whatsoever without proper attribution (author, copyright date)
First Printing: 2015
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Contents
Introduction .................................................................................................................................................. 8
Part 1: The Current State of Plastics ........................................................................................................... 10
Part 2: Disposal Environments and Management of Plastic Waste............................................................ 16
Chapter 1: Landfilling of Plastic............................................................................................................... 18
Section 1: Understanding Landfilling Rates ........................................................................................ 19
Section 2: Economics of Landfilling ..................................................................................................... 20
Section 3: Environmental Impact of Landfills ..................................................................................... 21
Section 4: Challenges of Landfilling .................................................................................................... 35
Section 5: Sustainability with Landfilling ............................................................................................ 36
Chapter 2: Recycling of Plastic ................................................................................................................ 38
Section 1: Understanding Recycling Rates .......................................................................................... 41
Section 2: Economics of Recycling ...................................................................................................... 43
Section 3: Environmental Impact of Recycling.................................................................................... 46
Section 4: Challenges of Recycling ...................................................................................................... 48
Section 5: Sustainability with Recycling .............................................................................................. 53
Chapter 3: Incineration of Plastic............................................................................................................ 56
Section 1: Understanding Incineration Rates ..................................................................................... 57
Section 2: Economics of Incineration .................................................................................................. 58
Section 3: Environmental Impact of Incineration ............................................................................... 59
Section 4: Challenges of Incineration.................................................................................................. 60
Section 5: Sustainability with Incineration ......................................................................................... 61
Chapter 4: Composting of Plastic ............................................................................................................ 62
Section 1: Understanding Composting Rates ..................................................................................... 68
Section 2: Economics of Composting .................................................................................................. 69
Section 3: Environmental Impact of Composting ............................................................................... 71
Section 4: Challenges of Composting .................................................................................................. 74
Section 5: Sustainability with Composting.......................................................................................... 77
Part 3: What Does Nature Do With Waste? ............................................................................................... 80
Part 4: Mimicking Nature with Biodegradable Plastics............................................................................... 84
Chapter 1: Defining Degradable, Biodegradable and Compostable ....................................................... 86
Section 1: Degradable Plastics ............................................................................................................ 87
Section 2: Biodegradable and Compostable Plastics .......................................................................... 90
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Chapter 2: Biodegrading traditional plastics........................................................................................... 94
Section 1: Creating Energy through Biodegradation of Landfilled Plastic .......................................... 98
Part 5: Testing and Validation for Degradable, Biodegradable and Compostable Plastics ...................... 100
Chapter 1: Degradable Testing ............................................................................................................. 102
ASTM D5272 - Standard Practice for Outdoor Exposure of Photo-degradable Plastics ................... 102
ASTM D5208- Standard Practice for Fluorescent Ultraviolet (UV) Exposure of Photo-degradable
Plastics............................................................................................................................................... 102
ASTM D7473 - Standard Test Method for Weight Attrition of Plastic Materials in the Marine
Environment by Open System Aquarium Incubations. ..................................................................... 103
ASTM D6954 - The ASTM D6954 is the Standard Guide for Exposing and Testing Plastics that
Degrade in the Environment by a combination of Oxidation and Biodegradation. ......................... 103
Chapter 2: Biodegradable Testing......................................................................................................... 104
Section 1: Importance of Microbial Diversity in Testing ................................................................... 105
ASTM D5988 - Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials
in Soil ................................................................................................................................................. 107
ASTM D5526 - Standard Test Method for Determining Anaerobic Biodegradation of Plastic
Materials under Accelerated Landfill Conditions.............................................................................. 108
ASTM D5511 - Standard Test Method for Determining Anaerobic Biodegradation of Plastic
Materials under High-Solids Anaerobic-Digestion Conditions.......................................................... 108
Biochemical Methane Potential ........................................................................................................ 109
Chapter 3: Compostable Testing........................................................................................................... 110
ASTM D6400 - Standard Specification for Compostable Plastics...................................................... 110
Part 6: Environmental Marketing of Plastics ............................................................................................ 112
Section 1: General Environmental Claims............................................................................................. 114
Section 2: Degradable and Biodegradable Claims ................................................................................ 115
Section 3: Recyclable Claims ................................................................................................................. 117
Section 4: Compostable Claims ............................................................................................................. 119
Part 7: A Sustainable Approach to Plastic Waste...................................................................................... 122
Resources Cited......................................................................................................................................... 127
About the Author: ..................................................................................................................................... 130
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Index of Figures
Figure 1: Worldwide plastic production 1950-2012. Includes thermoplastics, polyurethanes, thermosets,
adhesives, coatings, sealants and PP-fibers. Not included PTE-, PA-, and polyacryl-fibers. Source
PlasticsEurope (PEMRG) / Consultic ........................................................................................................... 10
Figure 2: European plastics demand by segment 2012. Source: PlasticsEurope (PEMRG)/ Consultic/
ECEBD .......................................................................................................................................................... 11
Figure 3: Plastics Generation & Recovery - US EPA .................................................................................... 12
Figure 4: Average cost of landfilling is a fraction of the cost to recycle, compost or incinerate (Cointreau,
2008) ........................................................................................................................................................... 20
Figure 5: Modern landfill design integrates gas collection to create value from biodegrading landfilled
waste ........................................................................................................................................................... 23
Figure 6: Conversion of complex materials to methane by microbial enzymes in municipal landfills ....... 27
Figure 7: Planetary boundaries showing the highest areas of concern are nitrogen, phosphorous, genetic
diversity all of which are in the zone of certain danger. Land system change is nearing the danger zone.
All of these criteria are directly related to farming. (Will Stephen, 2015) ................................................. 65
Figure 8: Natural carbon cycle made possible through biodegradation caused by microbial produced
enzymes ...................................................................................................................................................... 81
Figure 9: Degradable plastic is a category that encompasses many forms of breakdown. ....................... 87
Figure 10: Biodegradable plastics include home compostable, industrial compostable and landfill
biodegradable plastics. ............................................................................................................................... 90
Figure 11: Process of polymer biodegradation ........................................................................................... 95
Figure 12: Microbes utilize enzymes to release atomic bonds and rearrange the atomic structure of
materials ..................................................................................................................................................... 96
Figure 13: Energy/fuel value of biodegradable plastics in landfill gas energy projects (US only) .............. 98
Figure 14: Magnification of a polyethylene bag shows how it is made of millions of identical polyethylene
molecules that all have the same properties and the same biodegradability. If one molecule of
polyethylene biodegrades, so will the others. .......................................................................................... 100
Figure 15: Biodegradation tests attempt to replicate specific environments to ensure biodegradation will
occur in real world applications. ............................................................................................................... 104
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Introduction
Plastic is a versatile, inexpensive, durable and easily processed organic material that is used in an
enormous range of products. While plastic has in one form or another been used since the early 1900’s,
the use of and different types of plastics in the past 30 years has skyrocketed. Today, plastics have
replaced many traditional materials such as glass, metals, stone, ceramic, bone, wood and leather. This
transition to plastic has provided the means to preserve and protect food from spoilage, manufacture
items that are affordable to the majority, reduce product breakage, improve medical care and
innumerous other benefits. While the use and production of plastic articles continues to increase, the
disposal of plastic is becoming a critical issue.
Modern societies utilize several methods for managing the huge quantities of used plastic, including
landfilling, recycling, composting and incineration. While each of these options is used in varying
degrees, it is seldom that each of these methods is evaluated strategically from an economic and
environmental approach. Current infrastructure, social behavior and statistics of waste disposal should
also be a consideration when determining optimal ways to deal with waste. Understanding the whole
picture and taking each impact into consideration will provide a clear path to sustainable plastics
management.
The information contained in this paper will provide a clear picture of plastic disposal today and the
environmental, economic and social impact of landfilling, recycling, composting and incineration. The
information covered is beyond what one will find in most media reports and may at times seem
negative. This is not because there are not positive aspects to each subject; the information provided is
to be used in conjunction with the information provided regularly in media to create a balanced
perspective. It is expected that this common information will already be understood by the reader.
This paper then expands beyond the current methods of managing our waste and explores how waste is
processed within nature. Nature has been managing waste for millions of years in a very effective and
sustainable way. The closer we can replicate and integrate into the processes of nature, the more we
can truly become sustainable. Sustainability managers who incorporate the concepts presented in this
paper have the tools to implement solutions for their products and packaging that integrate effectively
and sustainably in the environment where their product is disposed.
Important note: This document is written in sections and it is not necessary to read each section in
order. If the reader has limited time and simply is looking for direction on how to design products for
sustainability, they may choose to simply read Part 7 which summarizes all the preceding information
and provides instructions for sustainable plastic management.
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Part 1: The Current State of Plastics
We are a society that requires plastic to maintain our standard of living; we use plastic in almost every
aspect of our lives. With 7.2 billion people on this planet, we use a LOT of plastic. World-wide the annual
production of plastic in 2012 was in excess of 600 billion lbs., or to put into perspective; enough plastic
to circle the earth one foot wide and one foot deep over 450 times!1 And the use of plastics is continuing
to increase, with consumption estimated to reach over 650 billion lbs. by the end of 2015. (PRWEB,
2015).
Figure 1: Worldwide plastic production 1950-2012. Includes thermoplastics, polyurethanes, thermosets, adhesives, coatings,
sealants and PP-fibers. Not included PTE-, PA-, and polyacryl-fibers. Source PlasticsEurope (PEMRG) / Consultic
1
The average weight for unbaled scrap plastic is 10lbs per cubic foot. 600 billion lbs would equal 60 billion cubic
feet. The circumference of the earth is 133 million ft. circling the earth with plastic one foot wide and one foot
deep would take 133 million cubic feet, we could circle the earth over 451 times with the production of plastic in
2012 alone.
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It is clear that the use of plastic is not going to decline anytime in the foreseeable future, and we will
continue to dispose of this plastic after use. As the production of plastic increases, so does the disposal.
We are producing plastics that will last nearly forever. Forty percent of the overall plastic made,
although extremely durable, is used for packaging, meaning it will most likely only be used for a few
months before it is disposed of. So, while some plastics may only be used for a few days or months and
others will be used for several years, there is no disputing that every ounce of plastic produced will at
some point become plastic waste that may last for centuries.
Figure 2: European plastics demand by segment 2012. Source: PlasticsEurope (PEMRG)/ Consultic/ ECEBD
With this immense amount of plastic becoming waste, how can sustainability managers ensure it is
disposed of in the most sustainable way? The first step in addressing the issue of plastic waste is to
understand where plastic is currently being disposed of after use.
When plastics first commercialized the only disposal of plastics was landfilling. The now infamous
"Garbage Barge" fiasco of 1987 in which a garbage barge left Long Island, NY carrying nearly thirty-two
hundred tons of garbage and was turned away at every port, created a panic. People began to believe
that landfills were running out of space and that we soon would have nowhere to dispose of our trash.
Fear of garbage piling up in streets and cities because there was nowhere else to put trash resulted in a
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new focus – diversion of waste from landfills.
Recycling was one of the initial methods utilized to divert valuable materials from landfills. As the
concept of recycling gained popularity, media and industry organizations began to demonize landfills.
Landfills were presented as wasteful, polluting and unsanitary – and this perception was justified
because the landfills at that time had significant environmental issues.
As the perception of landfills continued to decline, more methods were introduced to divert waste; we
began to burn our waste (incineration) and the idea of commercially composting plastics and organics
was born. The primary focus became finding every way possible of preventing any materials from
entering the landfill.
The idea of diverting from landfills has continued, and today we have become a society that loves to
hate landfills while adoring any method of diverting materials from a landfill. This approach would lead
one to assume that recycling, incineration and composting should by now be the primary disposal
methods for plastic. As is seen in Figure 3 below, after nearly 40 years of spending billions of dollars to
increase recycling, incineration and composting, we continue to landfill almost every pound of plastic
produced.
Figure 3: Plastics Generation & Recovery - US EPA
As sustainability managers look for new strategies to decrease their organizations environmental
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footprint, it is imperative to understand that while recycling, incineration and composting are an
important part of an overall sustainability strategy, our society still landfills over 90% of all plastics. Most
companies’ products and packaging will have nearly 100% disposal into landfills. This means that to
address a company’s products and packaging that will leave their facility, landfilling must be a focus or
the majority of waste will be overlooked. What this means is that a company must understand where
their products and packaging will be disposed of after use and build strategies around that environment.
Ultimately, multiple methods of disposal will be necessary to provide the most environmentally
sustainable and economically viable options for different types and forms of plastic. (Caraban, 2008)
Rather than attempting to create a ‘one size fits all’ program, which does not work, each material and
product must be evaluated separately; regional variations will come into play as well as social behavior.
Ultimately, an effective sustainability strategy will have to embrace solutions that include landfilling,
recycling, incineration, and composting in varying degrees. While this may sound daunting or complex, it
is fairly simple in practice once the details are understood.
Determining the optimal disposal method for a specific product, will include understanding the regional
waste management infrastructure and common method of plastic disposal. In the US, the primary
method of disposal is landfilling, with the remaining portions sent for recycling, incineration and
composting. The infrastructure is already in place to support landfilling as the largest repository for
waste; this is reflected not only by the number of facilities in the US, but also the total volume being
deposited in landfills each year.
Note: Litter is an aspect of overall waste, as plastics do end up littered in the
environment through both deliberate and unintentional littering. However, as visible as
litter is, litter equates to less than 1% of all plastics. Therefore, littering is not included in
this assessment. If a specific product has a high chance of being littered (i.e. shot gun
wads, cigarette butt, single use plastic bags, etc.) companies taking responsibility for
those products should develop product solutions that address littering which would
include biodegradability of the littered product in the open environment.
In the US there are approximately 1908 operating landfills, 633 material reclamation facilities (recycling)
and 86 incineration sites. (EPA, Municipal Solid Waste Generation, Recycling, and Disposal in the United
States, Tables and Figures for 2012) We have three times more landfills than we do facilities to accept
materials for recycling and 22 times more landfills than incineration sites. Sustainable strategies for
plastic must include landfill disposal.
In countries outside of the US, the number of landfills, recycling facilities and incineration sites will vary.
In Europe there are more incineration sites and recycling facilities, yet landfills are still the primary
location for disposal of waste. Recycling in Europe is typically limited to select plastics, metals, organics
and paper and does not significantly impact the landfilling of the non-bottle plastics, resulting in the
disposal of most plastic waste in landfills. There are a few countries within Europe that incinerate nearly
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50% of their waste, in these countries landfills are still used but to a lesser degree. Less developed
countries typically utilize landfills as the primary method of disposal for all wastes including plastics, at a
rate higher than the US.
The reality of where we dispose of our waste is often overlooked when sustainability initiatives focus on
reducing waste. The focus is most often on trendy subjects such as “zero waste”, “zero landfill”,
“compostable” or “recyclable”, which leaves sustainability managers misunderstanding the true picture
and how to create actual solutions. We will have little to no impact on overall waste unless we come to
terms with the fact that globally most all trash is put into landfills and we incorporate solutions that
involve landfilling.
To achieve the maximum value, both economically and environmentally, we must take a scientific
approach as opposed to an emotional response to our methods of waste management. This can mean
stepping back from what “feels good” to determine what is actually more environmentally beneficial.
Often our feelings about specific methods of disposal are influenced by the media, industry
organizations and regulators that may have specific agendas, don’t understand the full spectrum of our
waste systems or have commercial interests. The only way organizations will reach sustainability with
plastics is to step back look at the entire picture and evaluate the facts.
So let’s start with taking a look at how plastics are disposed of and what we can do to increase the
sustainability of these disposal methods.
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Part 2: Disposal Environments and Management of Plastic Waste
When our global approach to trash is to avoid discussing the truth of where our waste is going or
developing solutions based on those disposal environments, our global method of waste management is
at best ineffective. To achieve a sustainable mindset, we must accept the facts regarding our waste and
identify where plastic is currently being disposed and the impact of plastic in that disposal method. This
includes evaluating the resources required to transport, separate and process waste as well as the
efficiencies of these processes from an economic, environmental and social perspective.
Only once we understand and accept the facts of where and how our waste is disposed can we develop
solutions that are effective and impactful.
This part of the document will review in detail the methods society currently uses to discard plastics;
landfilling, recycling, incineration and composting. The part is organized into chapters that each focus on
a specific disposal environment. The chapters are ordered by the prevalence of the method; the
majority of plastics are disposed of in landfills so it is addressed first and very few plastics are
composted so this is covered last.
Each chapter is further divided into sections to focus on areas of concern such as how to correctly
interpret publicly reported rates of material, economic concerns, negative environmental impacts and
challenges specific to the disposal environment. Concluding each chapter is a section on sustainability
with information on how sustainability managers can design products to integrate most effectively in
the disposal environment being discussed.
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Chapter 1: Landfilling of Plastic
Landfilling is the oldest form of waste management; it involves the disposal of waste products by burial.
Worldwide, landfills continue to be the primary method to dispose of human waste. In regards to
plastics, landfills remain the most common method of disposal worldwide. In developing sustainable
strategies for plastics, we must include landfilling because most plastic is disposed of in the landfill. As
with recycling, incineration and composting, determining the sustainability options of landfilling requires
understanding the details of landfills and landfill operations.
Typically, landfills are controlled to avoid toxic waste, confined to as small an area as possible,
compacted to reduce their volume and covered (usually daily) with layers of soil. To accomplish this,
waste collection vehicles are inspected for any toxic waste upon arrival to the landfill. Once they are
cleared, they proceed to deposit the waste and compactors and bulldozers are used to spread and
compact the waste. There are many loads delivered each day to a landfill. At the end of each day, the
compacted waste is covered with soil or another alternative material such as crushed glass, compost, or
plastic film. This continues until the space is full.
This is a very simplistic overview of landfills and there are many details about landfills that are important
to sustainability and how we dispose of our waste. The economic and environmental sustainability of
putting plastic in landfills is affected by how the plastic is collected, what plastics are put into landfills
and the design and management of the landfills themselves.
This section is to provide a basic understanding of landfill design and management. It also covers landfill
gas, an energy rich gas that is produced as materials biodegrade in the landfill. Finally, we will see how
landfills fit within an overall sustainability profile and how to design products that will provide an
environmental and economic benefit in the landfill.
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Section 1: Understanding Landfilling Rates
Most would expect that the reporting of how much waste we send to the landfill would be pretty
straightforward, that it would mean how much material total is going into the landfill. Landfill statistics
are typically based on municipal solid waste only. Municipal solid waste is the trash that comes from
residential homes, apartment homes and some office buildings. What is not reported is industrial waste;
this is the waste from manufacturing, construction waste, demolition debris, and other industrial
processes.
Surprisingly, also not included in solid waste statistics is waste from recycling processes and the
waste/ash from incineration facilities. The process of recycling can produce a large amount of waste
both from materials that are baled but not wanted as well as from the recycling process itself, this waste
is sent to landfills but not reported as municipal waste. Similarly, after incineration the remaining ash is
nearly 25% of the original material weight and this ash is sent to landfills but not reported as municipal
waste.
The actual amount of material disposed of in a landfill is much higher than reported in statistics. This
means that more of our discarded material goes into landfills than is ever shown or reported.
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Section 2: Economics of Landfilling
Not only does most all waste worldwide go into landfills, they are also the most cost-efficient way to
dispose of waste. Recycling, incineration and composting all cost significantly more than landfilling. This
is because they require extensive investments in infrastructure, additional transportation vehicles, and
recycling also requires extensive manpower to maintain, whereas landfills have fewer fixed—or
ongoing—costs. In addition, landfill gas is a revenue stream opportunity for landfills that can offset or
even cover the costs of landfilling.
Average
To compare the costs of landfilling to other methods of plastics Disposal Method
Cost Per Ton
disposal consider the following: A sanitary landfill, which is one
that is managed to avoid groundwater air pollution, is the most
$
62.50
common type of landfill in developed nations and it costs Landfilling
$
108.50
municipalities/waste management organizations on average Recycling
$
115.00
$62.50/ton of waste material deposited. Recycling costs an Composting
average of $108.50/ton, composting costs an average of Incineration
$
175.00
Figure
4:
Average
cost
of
landfilling
is a
$115.00/ton and incineration is the most expensive at $175/ton.
fraction of the cost to recycle, compost or
(Cointreau, 2008)
incinerate (Cointreau, 2008)
The above landfill costs reflect the expense to collect waste and deposit it in the landfill, manage the
landfill and control the environmental impact of the landfill such as leachate, and air emissions. What is
not considered is the revenue that is generated when the landfill gas is collected and used as a fuel or
energy source. The revenue from landfill gas utilization can cover the entire costs of the landfill. Ideally,
this will provide a way to manage waste and generate clean energy in an economically sustainable way.
(Cointreau, 2008) Landfill gas is considered the most economical form of green energy available today,
even when considering the costs of hydro, solar and wind energy.
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Section 3: Environmental Impact of Landfills
More than 1.8 billion tons of waste is landfilled across the globe each year with most of this waste being
deposited in municipal solid waste landfills. (EPA, A Landfill Gas To Energy Project Development
Handbook). While landfills are the most inexpensive way to manage our waste, we must also consider
the environmental impacts. The common opinion is that landfills are wasteful and damaging to the
environment, however to make an accurate determination we must look at the facts and understand
the true impacts.
The negative image of landfills came from the way we designed and operated landfills decades ago.
These older landfills were often poorly managed which resulted in many environmental problems such
as;
1. Emissions to atmosphere such as noise, dust, odor, and bio-aerosols and landfill gas
2. Emissions to water which could include contaminated surface water run-off to local streams
and rivers as well as leachate seeping into groundwater below the landfill
3. Litter from wind blowing waste from uncovered landfills and animals getting into uncovered
landfills.
4. Fires that would erupt within the landfill, causing safety hazards and air pollution.
These issues were very problematic and lead to the development of modern landfills that control these
environmental impacts as well as develop ways to extract valuable resources from the landfill. These
landfills are called “modern landfills” and the management, design and environmental footprint is
completely different than the landfills of the 70’s and 80’s.
Today, U.S. landfills are regulated by each state's environmental agency, which establishes minimum
guidelines; however, none of these standards may fall below those set by the United States
Environmental Protection Agency (EPA). Understanding the design and operation of modern landfill can
overcome the misconceptions about landfills and provide a way to evaluate the value of modern
landfills.
We will focus only on modern landfills as they are the type of landfills where waste will be disposed of
today and in the future. Understanding the design and processes in modern landfills will provide a guide
to determining the impact and performance of discarded products in these environments. It will also
help in understanding what types of materials provide maximum value in the unique environment of a
modern landfill.
Section 3.1: Modern Landfill Design
For most, the term “landfill” conjures images of garbage, pollution and excessive waste. We imagine
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landfills filling at an enormous rate and the eventuality of the world becoming one large garbage dump.
Remember Disney’s 2008 movie “Wall-E” where the robot was tasked with cleaning up the abandoned,
waste-covered Earth? When we think of landfills, we envision billions of tons of trash mummified in
tombs that will never go away. What we don’t envision, however, is that through proper management
of these sites and management of our waste, landfills can be a source for clean inexpensive energy, a
process for detoxifying materials and a resource recovery facility.
It used to be that landfills were simply a location to store trash, but with increasing amounts of waste
generation and greater awareness of environmental issues, there has been a change in how we design
and manage landfills. This new approach includes landfills that are designed from the start to reduce the
environmental impacts seen in older landfills; they are lined to prevent groundwater contamination,
piping is installed to remove leachate and collect landfill gas, the landfill is covered daily to prevent
animals and wind from creating litter and the disposal of toxic waste is prohibited.
Modern landfills accelerate biodegradation to enhance gas generation, improve leachate quality, and
reduce leachate treatment costs. The enhanced gas generation refers to landfill gas or methane which is
generated during the biodegradation of materials within the landfill. This landfill gas is captured to
prevent atmospheric pollution, and is used as a valuable source of clean-burning alternative energy
(Wisconsin-Madison, 2011). Ultimately, the use of biodegradation within landfills has proven an
effective method to detoxify waste and create value. So how are landfills encouraging biodegradation?
Conventional sanitary landfills as practiced in North America in the 1970s and 1980s are generally
referred to as "dry tombs" because the approach taken in designing them was to minimize water
contacting the waste, primarily to try and reduce biodegradation and leachate formation. (Associates)
Modern research and technology has created a transition in the landfill industry from dry tomb landfills
to the bioreactor landfill and hybrid landfill energy site, where biodegradation is a primary objective.
The most widely used approach to increase the biodegradation within modern landfills is to increase the
moisture content through recirculation of leachate or addition of supplemental liquids (e.g., sewage or
industrial wastewater). (Wisconsin-Madison, 2011) The aim of operating landfills in this way provides
several benefits; the accelerated biodegradation of waste increases the methane production so landfill
energy projects can effectively capture the methane and convert it to a valuable resource – energy, fuel
and heat.
The modern process of capturing and utilizing landfill gas reduces the total methane released into the
atmosphere in comparison to the gas released into the atmosphere with older landfill designs. The
increased moisture/temperature conditions also induce the waste to settle creating more space in the
landfill and the ability to put more materials in the same space. Finally, the leachate is naturally
detoxified through biodegradation each time it is recirculated so groundwater and soil will not be
contaminated.
Designing landfills for biodegradation is an economic benefit to landfill operators. By producing more
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methane in a shorter period of time, say less than 50 years, landfill energy projects can become
profitable and often cover the costs of landfill operations. If the methane is produced more slowly over
longer periods of time, there is not enough methane produced on a regular basis to support the expense
or operation of energy conversion. Older landfills can take hundreds of years before they stop producing
methane, whereas modern landfills produce the majority of their methane within 50 years. (Associates)
The designs of modern landfills utilize the understanding of the biological processes occurring within the
landfill. These modern landfills focus on biodegradation for the purpose of generating methane, the
primary component in landfill gas, and the value of converting the resulting methane to energy. While
some of these landfills are built more recently and designed from inception for maximum capture of
landfill gas, increasing biodegradation and converting the methane to energy is so effective that
conventional landfills are also being retrofitted in a similar manner.
Landfills that are capturing the methane production and converting it to energy/fuel are called landfill
gas energy projects (LFG energy projects). Many landfills across the globe are currently using their
methane as a resource. Some of these LFG energy projects are part of the Global Methane Initiative
program. A program designed to promote the beneficial use of methane.
While many LFG energy projects are not registered with the Global Methane Initiative, we can look at
the number of ones that are registered to see the worldwide presence of these projects. Internationally
there are 1937 LFG energy projects registered with the Global Methane Initiative program. In the US
there are 967 projects producing 1044 million cubic feet per day of LFG that is actively converted to
energy (Initiative, 2015).
Figure 5: Modern landfill design integrates gas collection to create value from biodegrading landfilled waste
The U.S. Environmental Protection Agency (EPA) estimates that more waste is placed in landfills that
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capture methane to energy than landfills that allow the methane to escape into the atmosphere. In
2011, 35 percent of municipal solid waste went into landfills that capture methane for energy use, since
that time an additional 133 landfills are now converting methane to energy, over 80% of all municipal
solid waste goes into landfills that manage their methane. (Shipman, 2011)
Landfill design and operation have definitely evolved over the past few decades, providing a new
perception of landfills and changing the environmental impacts of those landfills. We no longer simply
bury the trash; today, landfills are highly managed resource centers where discarded material is
converted into energy through the natural process of biodegradation. While outside of the waste
management industry we don’t hear much about it, there are still advancements taking place that will
change the face of landfills completely.
Section 3.2: Biodegradation Process in Modern Landfills
There are different designs of landfills, conventional, modern and bioreactor, and while the design and
operation of these landfills differ; the biodegradation process remains the same. The primary change is
in the rate of biodegradation – does it take years, decades or centuries. Biodegradation in landfills takes
a different path than biodegradation in soil and compost. Primarily this is due to the lack of oxygen
(called anaerobic) in the landfill.
So, let’s talk biodegradation.
Biodegradation is the process by which organic substances (meaning carbon based) are broken down
into smaller compounds using the enzymes produced by living microbial organisms. The microbial
organism transforms the substance through metabolic or enzymatic processes. Although biodegradation
processes vary greatly, the final product is most often carbon dioxide and/or methane, soil, and water.
Biodegradable matter is generally organic material such as plant and animal matter and other
substances originating from living organisms, or man-made materials that are similar enough to plant
and animal matter to be put to use by microbes. Microorganisms have the astonishing ability to
biodegrade many different types of organic materials, including most all natural and many man-made
organic materials.
Organic material can be biodegraded aerobically (with oxygen) or anaerobically (without oxygen).
Biodegradable waste in landfill degrades in the absence of oxygen through the process of anaerobic
digestion. Anaerobic digestion is a series of processes in which microbes break down biodegradable
material in the absence of oxygen. It is widely used to treat wastewater sludge and biodegradable waste
because it provides volume and mass reduction of the input material. Anaerobic digestion also produces
biogas, an energy rich blend of methane and carbon dioxide.
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There are a number of bacteria that are involved in the process of anaerobic digestion including acetic
acid-forming bacteria and methane-forming bacteria. These bacteria feed upon the initial feedstock,
which undergoes a number of different processes converting it to intermediate molecules including
sugars, hydrogen & acetic acid before finally being converted to biogas.
The process begins when microorganisms break down insoluble organic polymers such as carbohydrates
into sugars and amino acids. Acidogenic bacteria then convert the sugars and amino acids into carbon
dioxide, hydrogen, ammonia, and organic acid. Acetogenic bacteria then convert these resulting organic
acids into acetic acid, along with additional ammonia, hydrogen, and carbon dioxide. Methanogenic
bacteria finally are able to convert these products into methane and carbon dioxide.
To put the above in more simplistic terms; biodegradation is the breakdown of a material from a
complex form to a much simpler and natural form. This breakdown is done by microscopic organisms
that produce extra-cellular enzymes that break apart the complex material and move around the atoms
to create simpler materials such as carbon dioxide, methane, water and soil.
Biodegradation can be a complex process that requires many different types of microorganisms and
different enzymes, but the final result is the same, complex materials are converted into the basic
building blocks of life, air, soil and water.
Landfill Decomposition Cycle
When the biodegradation process that occurs within landfills is looked at from a general standpoint, it is
clear that there are four primary stages. As a landfill ages, the conditions change and this requires a
change in the way material is biodegraded. At first there is some oxygen available and biodegradation is
aerobic, as the oxygen depletes the process transitions from aerobic to anaerobic. Here is a brief
description of the four primary stages:
Aerobic Phase – A very short period, often limited to just a few days, when aerobic microbes are
becoming established and moisture is building up in the refuse. Aerobic decomposition is at its
maximum and the oxygen is replaced with carbon dioxide (CO2) as the waste biodegrades.
During the final stages of this phase the anaerobic microbial populations increase by a factor of
100. (Barlaz, Microbiology of Solid Waste, 1996)
Anaerobic Acid Phase - After oxygen concentrations have declined sufficiently, the anaerobic
processes begin. During the initial stage (hydrolysis), the microbe colonies consume the
particulates, and through an enzymatic process, solubilize large polymers down into simpler
monomers. A rapid accumulation of carboxylic acids and organic intermediaries as well as a
decrease in pH occurs during this stage. CO2 production occurs rapidly at this stage and then
progresses to methane (CH4) toward the final stages. (Barlaz, Microbiology of Solid Waste,
1996)
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Accelerated Methane Production Phase – During this phase there is a rapid increase in methane
production to maximum concentrations of 70% CH4. During this phase, carboxylic acids and
organic intermediaries are consumed faster than they are produced. This results in an increase
in the pH and decrease in the carboxylic acid content. Microbial populations remain steady
during this phase. (Barlaz, Microbiology of Solid Waste, 1996)
Decelerated Methane Production Phase - The final stage of decomposition involves a decrease
in the CH4 production, although the CH4 and CO2 ratios remain steady at 60/40 relative. This
decrease results from a decrease in carboxylic acids. Polymer hydrolysis is maximized during this
phase; however the resulting carboxylic acids are decomposed at a similar rate to their
production due to a balance of microbial population. Humic material (soil) is produced during
this stage, similar to the humic matter produced during composting. (Barlaz, Microbiology of
Solid Waste, 1996)
In summary, the conditions in a landfill change over time, partially due to the reduction of oxygen and
partially due to the by-products of biodegradation. The decomposition process in landfills demonstrated
above is a process that requires a coordinated effort between several groups of micro-organisms. The
decomposition products from one group of bacteria become the food source for another group of
bacteria until the complete decomposition is finalized. While the process may change during the four
stages of the landfill, biodegradation continues until all the organic material is decomposed completely.
Microbial Biodegradation of Materials in Landfills
When a material biodegrades it does not typically convert directly from a complex material into air, soil
and water. Biodegradation is a process where one type of microorganism will take the complex material
and break it down into a simpler material. That simpler material is then used by a different type of
microorganism that breaks it down even further. This process continues until the material is completely
biodegraded. This is what is meant by the “phases of biodegradation”.
In a landfill, the primary method of biodegradation is anaerobic. There is some oxygen in the initial days
of a landfill but this oxygen is quickly used up and the environment becomes anaerobic. Anaerobic
biodegradation occurs when the anaerobic microbes are dominant over the aerobic microbes (because
there is not much oxygen for the microbes to use).
The anaerobic biodegradation process begins with bacterial hydrolysis and fermentation of complex
organic structures to smaller low-molecular-weight insoluble organic acids, such as carbohydrates (e.g.
acetate). These smaller compounds can be used by some bacteria to be directly mineralized to CO2.
Acetogenic bacteria then convert the low-molecular-weight organic acids (sugars and amino acids) into
carbon dioxide, hydrogen, ammonia, and acetic acids. Methanogenic bacteria finally are able to convert
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these products to methane and utilize hydrogen as an energy source.
There are four key biological and chemical stages of anaerobic digestion; hydrolysis, acidogenesis,
acetogenesis and methanogenesis. In most cases waste in the landfill is made up of large organic
polymers, both natural and synthetic. In order for the bacteria to access the energy potential of the
material, these chains must first be broken down into their smaller constituent parts. These constituent
parts or monomers such as sugars are readily available by other bacteria.
The process of breaking down these complex chains and dissolving into smaller molecules is called
hydrolysis. Therefore hydrolysis of these complex
materials is the necessary first step in anaerobic
digestion. Through hydrolysis the complex organic
molecules are broken down into monomers; simple
sugars, amino acids, and fatty acids.
The biological process of acidogenesis is where
there is further breakdown of the remaining
components by acidogenic fermentative bacteria.
Here VFAs are created along with ammonia, carbon
dioxide and hydrogen sulfide as well as other byproducts. The process of acidogenesis is similar to
the way that milk sours.
The third stage anaerobic digestion is acetogenesis.
Here simple molecules created through the
acidogenesis phase are further digested by
acetogens to produce largely acetic acid as well as
carbon dioxide and hydrogen.
Figure 6: Conversion of complex materials to methane by
microbial enzymes in municipal landfills
Acetate and hydrogen produced in the first stages can be used directly by methanogens (a type of
microorganism). Other molecules such as volatile fatty acids (VFA’s) with a chain length greater than
acetate must first be catabolized into compounds that can be directly utilized by methanogens.
The terminal stage of anaerobic digestion is the biological process of methanogenesis. Here
methanogens utilize the intermediate products of the preceding stages and convert them into methane,
carbon dioxide and water. The majority of the biogas emitted from landfills is methane and carbon
dioxide; there may also be other trace gases depending on the material being biodegraded.
Anaerobic biodegradation ultimately produces methane as the final biogas.
Biodegradation in landfills is a complex process that involves hydrolysis, fermentation, acetogenesis and
methanogenesis. It requires the concentric effort of various methanogenic bacteria, acetogens,
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protozoa and flagellate. The complexity of the process does not mean that it is not effective or efficient.
Landfills are a thriving ecosystem of biological diversity and modern landfills optimize this process for
biodegradation.
Section 3.3: Landfill gas
Landfill gas (LFG) is created as organic waste in a landfill biodegrades anaerobically, as demonstrated in
the previous sections. This is a similar process as is seen in other anaerobic environments that produce
methane, such as swamps, animal intestines and anaerobic digesters. All of these are natural processes
that produce methane as microorganisms reorganize the hydrogen and carbon from complex materials
into simpler structures such as methane –CH4 (one carbon atom and four hydrogen atoms) and carbon
dioxide – CO2 (one carbon atom and two oxygen atoms). This gas consists of about 50-70 percent
methane (the primary component of natural gas) and about 30-50 percent carbon dioxide.
In the past, landfill gas was a problem because it was not controlled and collected. Today, both
European and US EPA law requires that landfill gas be collected and utilized. This prevents negative
environmental impacts that the gas could otherwise cause, such as global warming effect. Utilizing the
gas is also a sustainable way to manage our resources by producing energy and fuel.
The Value of Landfill Gas
Modern landfills collect landfill gas and convert it to energy or use it as fuel for vehicles. Using landfill
gas for energy is both environmentally and economically valuable. Landfill gas is a consistent, reliable
and proven renewable energy source, and when converted to energy, reduces a community’s carbon
footprint. From an economic viewpoint, when the energy is sold, landfill gas provides a revenue stream
that can often cover the entire expense of the landfill.
In 2014, the US had 636 operational LFG energy projects in 49 states/territories that supplied
approximately: 16 billion kilowatt hours of electricity, and 100 billion cubic feet of LFG to end users.
Annually, LFG energy projects produce enough energy to power nearly 1.2 million homes for a year and
heat more than 731,000 homes. (EPA, Green Power from Landfill Gas, 2015)
LFG energy projects help to curtail global climate change, because they reduce emissions of methane, a
greenhouse gas more potent than CO2. Reducing LFG emissions by converting them to energy reduces
local ozone levels and smog formation, diminishes explosion threats, avoids unpleasant odors created
by the landfill, and improves overall landfill management. The United Nations Development Program
recognizes the use of methane from anaerobic biodegradation as one of the most useful decentralized
sources of energy supply.
Landfill gas is used in a variety of ways, as liquid fuel, gaseous fuel and direct conversion to electricity.
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One option is for utilities and power providers to purchase the electricity generated from the recovered
LFG. Purchasing electricity from LFG enables utilities and power providers to add a renewable energy
component to their energy portfolios. LFG can also be piped directly to a nearby facility for use as either
a boiler or industrial process fuel. Direct use of LFG is reliable and requires minimal processing and
modifications to existing combustion equipment. Landfill gas is also used as a replacement to natural gas
to fuel vehicles.
Waste Management is the largest waste management company in North America, not only do they
operate many landfill gas projects, but they also use landfill gas to fuel some of their collection vehicles.
The 300 collection trucks in Livermore, California are fueled by compressed landfill gas from the same
landfill they service. This landfill produces up to 13,000 gallons of liquefied natural gas each day.
(Lozanova, 2008)
From the commercial waste management perspective, their position is; “the greatest danger to landfills
is contaminating the air, so we suck the gas out and use it for energy recovery. It’s green energy. Gas
from an average-sized landfill in the United States could provide a consistent energy supply for up to
4,000 homes. People have this mindset that we’re only waste companies, but we’re also recycling and
energy supply companies. We need to change people’s perception.” (Kudialis, 2015)
The benefits of LFG energy in terms of greenhouse gas emission reductions are substantial. For example,
a 3 megawatt LFG energy facility requires approximately 1,075 standard cubic feet per minute (scfm) of
LFG to operate. Not only does the combustion of this quantity of methane in an LFG energy facility result
in direct methane emission reductions, but also in indirect CO2 emission reductions of about 11,950
metric tons per year (depending on the type of fuel that was used to generate the displaced electricity).
The indirect environmental benefits of fossil fuel displacement through LFG energy can amount to
nearly 10 percent of the direct greenhouse gas emission reduction benefits from methane combustion.
The direct and indirect CO2 equivalent (CO2e) emission reductions from a direct–use project utilizing
1,000 scfm of LFG are approximately 126,000 and 12,440 metric tons per year, respectively. Twenty-two
states and the District of Columbia have renewable portfolio standards (RPS), requiring that electricity
producers obtain a certain amount of their power from renewable sources. In most of these states,
waste-to-energy facilities and landfill gas are considered renewable energy sources. (EPA, Solid Waste
Management and Greenhouse Gases, 2006)
The annual environmental benefits from current landfill gas-to-energy projects are equivalent to;
planting over 20.5 million acres of forest per year, preventing the use of over 177 million barrels of oil,
removing the carbon dioxide emission equivalents of over 14.5 million cars, or offsetting the use of
370,000 railcars of coal. Silicon Valley is also utilizing energy from landfill gas to meet its obligations
under the California Renewable Portfolio Standard which requires 33 percent of total energy come from
renewable sources. (Defreitas, 2011)
LFG energy projects provide significant cost savings and long-term sustainable energy to LFG end users.
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Some recent examples include: (Source list from US EPA) (EPA, Green Power from Landfill Gas, 2015)
o
o
o
o
Coca-Cola’s Atlanta Syrup Branch facility gets nearly all of its energy in the form of
electricity, steam and chilled water from green power generated at a nearby landfill,
providing Coca-Cola with real energy savings. The landfill annually generates 48 million
kilowatt-hours of on-site green power.
The U.S. Navy saves approximately $1.1 million annually in utility costs at the Marine
Corps Logistics Base located in Albany, Georgia, since its first LFG cogeneration plant
was completed in 2011. This facility is made up of a dual-engine generator, a heat
recovery steam generator and two dual-fuel boilers.
In 2012, Gundersen Health System’s Onalaska Campus became the first energyindependent medical campus in the United States by using LFG piped from the local
landfill in La Crosse County, Wisconsin. The LFG is used to power a generator that
supplies 100 percent of campus energy needs.
The U.S. Department of Justice obtains 80 percent of its Federal Bureau of Prisons’
Allenwood Correctional Complex’s electricity from the combustion of LFG at the nearby
landfill in Lycoming County, Pennsylvania.
The benefits of LFG energy are also well recognized and include: (Source list from US EPA) (EPA, A
Landfill Gas To Energy Project Development Handbook):
o
o
o
o
o
o
o
o
o
o
LFG is recognized by energy certification programs as a renewable energy resource.
LFG serves as the “baseload renewable” for many green power programs, providing
online availability exceeding 90 percent.
Most states have landfills that can support LFG projects.
Energy produced from LFG is least expensive form of renewable energy.
Landfill gas comes from local sources, and it usually costs less than conventional fuels.
Landfill gas energy recovery is a proven technology.
Landfill gas recovery projects provide a net environmental benefit by reducing methane
and volatile organic compounds emissions, conserving fossil fuels, reducing explosive
hazards, and reducing odor.
Landfill gas projects can serve on-site electrical loads at dispersed locations, thus
reducing the need for new generating plants and transmission facilities.
Landfill gas projects offer a way for utilities to attain Climate Challenge voluntary
greenhouse gas emission reduction targets.
Title IV of the Clean Air Act (Acid Rain Program) creates a quantifiable value for avoided
SO2 emissions.
Landfill gas is used worldwide as a proven and reliable source of renewable energy; it is used for many
purposes such as in conversion to electricity, heat and fuel for vehicles. Landfill gas energy is providing a
way for communities to reduce their carbon footprint and comply with rigorous renewable energy
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requirements. Landfill gas is an important part of overall sustainability not only for how we dispose of
materials but also how we create energy.
Section 3.4: Importance of Biodegradation Rates
The capture and use of landfill gas is critical in the overall sustainability profile of a landfill. One of the
most important factors in capturing landfill gas is making sure the systems are in place to collect the gas
when that gas is produced. This will mean balancing the time frame between when biodegradation
produces the gas and when the landfill can collect that gas. If a material biodegrades too quickly in the
landfill, the landfill gas collection system will not yet be installed and the gas will escape to the
atmosphere. Similarly, if a material biodegrades too slowly in the landfill, the collection system will have
been removed and the landfill gas will again escape into the atmosphere. For optimal environmental
value a material should biodegrade during the time that the landfill gas is being collected.
Landfill and LFG collection operations in the United States are well established and more than 90
percent recovery can be achieved at cells with final cover and an efficient gas extraction system. (EPA,
LFG Energy Projects) This means that less than 10% of the methane is not converted to energy. However
this efficiency is dependent on the design of the landfill as well as the length of time the waste has been
within the waste environment. So how can we not only manage landfills but also design products for
maximum value in the landfill?
Most landfill gas collection systems are installed within two years at a landfill site. Once the collection
system is in place, it will continue to collect the landfill gas until the material in the landfill is
biodegraded and the gas production stops or becomes minimal. The period of time where the gas is
actively collected is considered the “managed life” of a landfill and it will start once the gas collection
system is in place and continue for up to 50 years after the landfill stops accepting waste.
As you may recall, a landfill has four primary phases of biodegradation. The first two phases, aerobic and
anaerobic acid phases, produce primarily carbon dioxide and smaller amounts of methane. It is not until
the third and fourth phases, the accelerated methane production and decelerated methane production
phases, when the majority of methane is generated; between 40 and 70 percent of total volume.
(Associates) The third and fourth phases are the most critical time to have the landfill gas collection
system in place.
Typically, the waste in most landfill sites will reach the stable methanogenic phase within less than 2
years after the waste has been placed into the landfill. Depending on the depth of the waste, the type of
waste and the moisture content of the waste; the methanogenic phase might be reached as early as six
months after placement.
It may initially appear that rapid movement into the fourth phase and the resulting methane production
would be most beneficial. However, studies show that more rapid biodegradation may actually be
environmentally harmful. During the first two years there is often no collection system in place for the
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gas. If materials break down and release methane quickly, much of that methane will likely be emitted
before the collection technology is installed. This means less potential fuel for energy use, and more
greenhouse gas emissions. (Shipman, 2011)
As a result, a slower rate of biodegradation is actually more environmentally friendly, because the bulk
of the methane production will occur after the methane collection system is in place. (Shipman, 2011)
Ideally, the majority of biodegradation, and the resulting methane, should take place after the collection
system is in place and biodegradation should complete during actively managed post closure (50 years).
In this scenario, the collection of methane is most likely to reach the 90% efficiency.
There has been some confusion as to what time frame a material should biodegrade to be considered
“biodegradable”. In the US there has been talk of a one year limitation. For composting there is a 6
month limitation, however in landfills the optimal time frame is much different. Biodegradation in
landfills should occur during the managed life of the landfill, specifically 2-50 years. This should clarify
the confusion regarding the definition of biodegradable, products labeled as biodegradable should
biodegrade in the optimal time frame for the relevant disposal environment.
This problem may be exacerbated by the US Federal Trade Commission (FTC) guidelines call for products
marked as “biodegradable” to decompose within “a reasonably short period of time” after disposal2.
However, if a material is to biodegrade in less than one year in the landfill, all of the landfill gas would go
directly into the atmosphere because there is no collection system in place. This means less potential
fuel for energy use, and more greenhouse gas emissions. (Shipman, 2011)
We must design the products to integrate into the most optimal process time of the landfill, this means
biodegradation that occurs primarily during the managed life of the landfill. As was stated by Morton
Barlaz of NC State; “If we want to maximize the environmental benefit of biodegradable products in
landfills, we need to both expand methane collection at landfills and design these products to degrade
more slowly – in contrast to FTC guidance.” (Shipman, 2011)
Recently an FTC judge upheld this position by ruling that biodegradation is an inherent feature of a
material and that the one year limitation previously identified by the FTC was not applicable. Regardless
of the popular view of biodegradable time frames, from an environmental perspective the most
beneficial time frame for biodegradation within the landfill is from 2-50 years.
Most food and garden waste is expected to biodegrade within 1-3 years, whereas paper, yard waste and
slower degrading materials would biodegrade in 10-50 years. (Associates). This indicates there may be a
2
Note: The US FTC regulations do not require biodegradation within one year, the guidelines state that
products that biodegrade in greater than a year must be marketed with a qualification statement that
includes the rate, environment and extent of biodegradation validated. More clarification is provided in
the section “Marketing of Sustainability in Plastics”.
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benefit to diversion of food waste from landfills as the methane production from these materials would
most likely be released directly into the atmosphere.
When considering the environmental impact of plastic in the landfill, how fast it biodegrades is the most
important factor. We must move away from the notion that faster biodegradation is better and look at
the facts. If a plastic biodegrades in less than 2 years you could be causing environmental harm,
similarly, if it biodegrades too slowly, more than 50 years, you have the same negative environmental
harm. Both can cause harm because of the landfill gas that will go directly into the atmosphere and
contribute to global warming.
So, although over 75% of all MSW is placed in landfills managing biogas (Dr Morton Barlaz, NC State),
the management is less effective when the waste biodegrades too quickly or too slowly. Thus it is
important from an environmental perspective plastics should be designed to biodegrade within the
managed life of a landfill which is 2-50 years. Controlling the rate of biodegradation to the managed life
of the landfill will ensure that the landfill gas is captured and converted to a resource that increases our
green/renewable energy profile, reduce the energy needs from coal, reduce the carbon footprint of
both the plastic and the landfill, and provide the most economic value as the energy/fuel is sold.
Section 3.5: Advancements in Landfill Design
The most recent development in landfill design is called a bioreactor landfill. Bioreactor landfills are
focused solely on accelerating biodegradation as quickly as possible. Not only is moisture used to
increase biodegradation, but often the temperature, oxygen levels, microbial colonies and pH levels are
monitored and controlled.
Some bioreactor landfills are designed to not only biodegrade material quickly, but are also designed to
be reused. This means that the waste goes into the bioreactor landfill, it decomposes and then the
resulting soil is dug up, used as a soil amendment and the landfill space is reused for more waste.
Note: This may sound similar to industrial composting, but it is significantly different.
Bioreactor landfills accelerate the rate of biodegradation in comparison to other landfill
designs; however it is still slower than would be seen in industrial composting. Bioreactor
landfills are designed to take mixed waste (everything that goes into the garbage can)
while composting uses sorted organic waste. Also, bioreactors produce both methane
and carbon dioxide through anaerobic biodegradation, whereas composting is aerobic
and produces primarily carbon dioxide.
The design of bioreactors accelerates the biodegradation so effectively that the bioreactor can hold up
to 30% more waste in the space of a modern landfill. As materials biodegrade they reduce in size and
the overall mass of the landfill declines, creating more space for placing more waste. With increasing
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amounts of waste produced every year, bioreactor landfills provide a significant way of maximizing
landfill space. This is not just cost effective, but since less land is needed for the landfills, this is also
better for the environment.
Furthermore, once a landfill is closed it must be monitored for at minimum 30 to 40 years to ensure
leachate or landfill gases are no longer an environmental impact. With bioreactor landfills, the
accelerated biodegradation can reduce the time of monitoring down to less than 10 years.
Biodegradation is the key to detoxification. Once a material has biodegraded, there is no additional
methane production and toxicities have been removed. Accelerating the biodegradation stabilizes the
landfill and removes toxins much faster. This allows the land to be used much more quickly and safely
for other purposes such as community parks and reforestation without risk of contamination or danger.
Using the landfill space multiple times is another potential benefit of bioreactors. While not currently
practiced, some bioreactor landfill designs provide a way for the soil to be dug up once biodegradation is
complete. By reusing the space, it would not be necessary to build new landfills. Once the landfill is done
biodegrading, it would be dug up, the metals and non-biodegradable materials sorted out and the
remaining soil would be similar to compost and used as a soil amendment. This is a very sustainable
method of landfilling.
Today, there are only a handful of bioreactor landfills in operation as the design is fairly new. However
the environmental and economic value these offer will pave the way for the complete conversion of all
landfills to this design. Ultimately, bioreactor landfills are not landfills at all; they are more similar to
anaerobic digesters where the organic material biodegrades into soil, air, water and methane, the
methane is captured and converted to energy and then the resulting non-biodegradable material can be
sorted out for recycling or reuse.
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Section 4: Challenges of Landfilling
The prevalence of landfilling has made landfills the most mature infrastructure available for
management of waste materials. The primary challenge with the landfilling of plastics not in the design
of landfills as they are well designed and well maintained, the challenge is in the engineering of plastics.
Plastics should be engineered to biodegrade during the managed life of the landfill so the methane can
be captured and utilized for energy.
Today over 90% of plastics are disposed of within landfills where they will slowly biodegrade over
centuries. For many companies products and packaging closer to 100% of the plastic will be landfilled.
During the biodegradation of plastics methane is produced. Because the methane is produced over such
a long period of time, it is not captured but instead it is released into the atmosphere.
Technology is currently available that accelerates the biodegradation of plastics in the landfill so that the
plastics will biodegrade during the managed life of the landfill. This allows the energy value to be
utilized, and reduce volume in the landfill.
Another challenge is the public perception of landfills. There is a general negative impression regarding
landfills and sustainability, a belief that nothing should ever go into a landfill. This view inhibits the
adoption of technologies that improve the sustainability of landfills because some are slow to accept the
truth that plastics are and continue to be disposed of in the landfill. The result is that many companies
continue producing traditional plastics that will be disposed of in landfills where there is no
environmental value rather than incorporating technologies that accelerate the biodegradation of
landfilled plastics for optimal environmental value.
The challenges of plastics in the landfill can easily be overcome through education. The technologies for
sustainability manager to incorporate landfill biodegradable plastics are available today and the landfill
infrastructure is already in use, now it is a matter of implementing the technology.
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Section 5: Sustainability with Landfilling
When considering landfills from a sustainability perspective, often the most difficult thing is to step back
from the negative notions of landfills. Too often, sustainability managers get caught in the trend of “zero
landfill” because it is great marketing and it sounds like it would be more environmental. We must
overcome the negative perception of landfills so we can evaluate them objectively.
The truth is always in the facts. Landfills are an important part of any sustainability strategy. Most all of
the waste worldwide goes into landfills. Landfills can be the most environmentally and economically
beneficial disposal options for certain items. Technology has completely changed landfills; they are not
the same as they were prior to the 1980’s. And landfills are an important part of many municipal green
energy initiatives.
Landfill design and operation has completely changed over the past few decades. Landfills are now
actively managed to avoid leachate absorption into the surrounding soil, to avoid air emissions and they
are a valuable and consistent source of renewable energy. Modern landfills are by far the most
inexpensive method to dispose of materials and they allow a means to provide economic and
environmental value through the conversion of landfill gas to energy.
There is no doubt that most all plastics are disposed of in landfills. Even after 40 years of efforts to divert
plastics from landfills, we still landfill over 90% of plastics. Many companies’ products and packaging will
have closer to 100% landfill disposal. History has shown that we will continue to landfill plastics for a
very long time and attempts to divert plastics from landfills usually causes more damage to the
environment and economy than any benefit it may provide. Because of this, we must understand how to
create sustainability with landfilling of plastics.
Plastics in the landfill should biodegrade during the managed life of the landfill, 2-50 years. When
compostable plastics enter a landfill many will biodegrade too rapidly and the methane is released into
the atmosphere and most traditional plastics biodegrade over hundreds of years meaning, again, the
methane goes into the atmosphere. We must use plastics that biodegrade during the 2-50 year
managed time of a landfill so the methane can be managed, collected and converted to clean energy.
Once collected, the methane provides energy, fuel, and reduces the methane's global warming effects.
Ultimately, we cannot disregard landfilling because plastics are, and will continue to be, discarded into
landfills. Instead, we must design plastics that provide value in the landfill. In this way, we can create a
sustainability platform that is realistic and beneficial.
From a sustainability perspective, traditional plastics should never be disposed of in a landfill.
Companies producing products that will most likely be disposed of in a landfill should not use traditional
plastics alone; they should use landfill biodegradable plastics to provide the maximum environmental
benefit upon disposal.
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Chapter 2: Recycling of Plastic
In any conversation related to plastics and sustainability, recycling is an inevitable topic. Remember the
garbage barge fiasco of 1987? As a result in 1988, Winston Porter of the US EPA first set national
recycling goals as a more effective way to manage certain waste. This was a simple message of removing
valuable materials from the waste stream so they could be reused for another purpose, and it has
become a very valuable part of sustainability.
The idea of keeping valuable materials out of the landfill has evolved into the modern message of
“recycle everything, regardless of the costs”. From a recycling perspective, there is the notion of a world
without landfills, where all plastic products are kept in a continual cycle of use, collection and reuse.
There are some in the industry that go as far as to claim ‘any process other than recycling of plastic is a
waste of the molecule’.
The thought here is that we have put resources into creating a molecule of plastic and that by sending it
to a landfill we are wasting the energy and resources we used to create it. But what if recycling that
molecule takes more resources and causes more harm to the environment and economy than other
methods of disposal? To evaluate this further we should also consider the resources needed to replace
the molecule that was not recycled. In essence, to know if recycling a specific material is beneficial we
must know which requires the least amount of resources; recycling the material or disposing of it in a
sustainable way and creating new molecules?
This idea has become so extreme and entrenched that some feel recycling is a moral obligation that
should be done at any cost. There is also the idea that regardless of the resources required recycling is
always more environmental. It is seldom that the details of recycling, including the true costs and
impacts are discussed openly. We have to start critiquing recycling with the same scrutiny as with any
other waste management process to ensure the result is both economically and environmentally
beneficial. Studies show that while recycling of some materials can be environmentally beneficial,
attempting to recycle other materials can be both environmentally and economically costly.
There is no doubt that certain plastics can and should be recycled. PET beverage bottles and HDPE
bottles are a prime example of ideal plastics to recycle. These two products have proven success in
current recycling processes, providing they are not colored, blended with other plastics or combined
with other materials. They are available in large quantities, easy to identify, relatively uncontaminated,
simple to process and have resale value. But what about the other types of plastic?
Instead of aiming for specific recycling rates, cities should aim for making an environmental difference,
says J. Winston Porter, who, as former assistant administrator for America's Environmental Protection
Agency, was the first to establish nationwide recycling targets in the United States in the 1980s. His
target then was 25%, and it's a number he largely sticks by. Diverting 35% of waste into recycling is
about as a high as any city can justify, he says.
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Trying to recycle more can be wasteful, if not harmful, he says, even though many major cities are
setting targets at 70% or higher. "People say you can't recycle too much. It turns out you can," says Mr.
Porter, president of the environmental consulting firm, the Waste Policy Center, near Washington, D.C.
"If you spend enough money, you can recycle anything. That doesn't mean you should." (Libin, 2009)
In a recent Perspective article, Bill Sheehan and David Kirkpatrick asked, “Is zero waste, which means
recycling nearly everything, achievable?” The answer is provided by Winston Porter, the originating
father of the US EPA recycling directive:
“No. Not only is 100 percent recycling not reachable, but it is not even good for the
environment. Georgia and the nation are recycling more than 25 percent of their trash,
thus meeting the national goal I set in 1988 while an assistant administrator at the U.S.
Environmental Protection Agency. However, most areas are not going much higher than
30 percent to 35 percent recycling for several reasons. First, at least one-fourth of
trash—including such items as kitty litter, paper towels, dirt and broken toys—is virtually
non-recyclable because it is hard to collect and has almost no value. So to reach even 50
percent recycling, about two-thirds of every “recyclable” item would need to be
recovered. Second, only a few of the 50 or so identifiable items in garbage are present in
significant percentages: cardboard boxes (13 percent of trash) and newspapers (6
percent), to name two. Those items are already recycled at high rates. To increase
overall recycling dramatically, we would have to go after dozens of “one-percenters,” at
great cost and inconvenience to consumer. How about 15-20 recycling bins at your curb?
There’s more. It is often difficult and expensive to recycle in rural areas. And much of our
recycling is voluntary—we can’t force everyone to do it. Finally, we have to sell our
recyclables, which is not easy when prices for these commodities soften, as they do
periodically. The zero-waste notion begins with the false assumption that reuse or
recycling is always best for the environment. In March 1996, I conducted a study of
reusable vs. disposable food service packaging, analyzing more than 30 European and
American environmental investigations. The basic result was that a disposable package
or container (e.g., a foam coffee cup) is preferable to a reusable one (e.g., a porcelain
cup) from the standpoint of water supply and water pollution, since washing the
reusable cup creates hot, soapy wastewater. Disposables are also safer from a public
health viewpoint. The reusables are better from air and solid waste standpoints, but only
if reused several hundred times.
It is apparent that the zero-waste advocates are talking about zero solid wastes. But
what about air and water pollution or energy usage? Not to mention the negative
economic impacts of pursuing such a pie-in-the-sky venture. Also, modern landfills,
demonized by Sheehan and Kirkpatrick, have to meet very stringent federal and state
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regulations and pose very small environmental risks.
Finally, the zero-waste concept ignores the law of diminishing returns. We already
recycle the items that make the most environmental and economic sense. As we force
ourselves to go after less valuable wastes in more difficult locations—say, hotdog
wrappers at ballparks or leftover napkins at the airport—the costs will skyrocket.
Recovered items will be trucked greater distances, or more resources will be used to
clean and process dirty recyclables.
Our goal should be to minimize the overall environmental impact of our products, not
simply to shut the door in one area—solid wastes. And every dollar spent on zero waste
is a dollar taken away from other environmental problems or from such areas as
education, health care, or transportation.” (Porter, Too much recycling can be a waste of
resources, 1997)
Recycling is an important part of an overall sustainability strategy, but we must look at the facts. While
the media is quick to report on aspects of recycling that appear to be successful, the recycling industry
promotes that the increased collection of materials is a success, and society continues to believe that
recycling is the key to being sustainable; we have yet to achieve sustainability.
If we want to be a sustainable species, we have to look at the scientific data and not blindly assume that
we must recycle all items and that it is always beneficial to recycle. We must understand the economics
and environmental impacts of recycling so we can determine when it is beneficial to recycle.
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Section 1: Understanding Recycling Rates
In different regions of the world the definition of “recycled” can vary significantly. Some countries define
recycling as simply the collection of materials, while others consider burning plastic (incineration) as
recycling, and others determine recycling by the material that is actually remanufactured into new
products. Without a standardized definition of what recycling means, it can be difficult to interpret the
reports of recycling rates. For example, in Europe, incineration of plastic is very common and is included
in plastic recycling statistics.
In 2014, Sweden published a recycling rate of 99% - their definition of recycling included incinerating
nearly 50% of their trash. (inhabitat.com, 2014) Minister Auken of Denmark, in 2013 stated that
Denmark incinerates nearly 80% of household waste, which is again considered as recycling. (ZeroWaste
Europe)
Similarly, Europe is often considered the leader in recycling of plastics and reports over 50% recycling of
plastics. The details of their report show that only 19% was actually recycled and the remaining 30.3%
was incinerated. (Plastemart.com) European countries reporting the highest “recycling” rates incinerate
at a minimum 50% of their waste and include the incineration of plastic as part of the total recycling
rates. The inclusion of incineration of plastic within recycling rates is causing a rising debate regarding
the definition of recycling, because the environmental and financial impacts of recycling and
incineration are much different. (Seltenrich, Incineration versus Recycling: In Europe, A Debate Over
Trash, 2013)
Note: The following information is presented to provide a clear understanding of current
recycling rates; it is not to discount the importance of recycling or to discourage
recycling. The information is provided so sustainability managers can interpret recycling
rates accurately and assess the current status of recycling, to know if recycling efforts
are being successful for their types of products and evaluate if their products and
packaging will be recycled.
Some misunderstand how recycling is reported and think that a reported figure for recycling includes all
types of plastic. With paper and glass, the recycling rates are reported as a total figure, all the different
forms of the material are included in a single number. With plastics, they are not grouped into a single
category; instead certain subcategories are separated and then reported. For example, recycling of PET
single use beverage bottles is a reported subcategory. Currently single use PET beverage bottles are
reported at 32% recycle rates. This means that of the single use PET beverage bottles produced, about
32% of them were collected for recycling. However, this is only related to single use PET beverage
bottles and should not be extrapolated to other types of plastic.
PET bottle recycling rates are calculated by taking the how many bottles were produced by
manufacturers (production) and comparing it to the amount of PET collected at recycling facilities
(collection). The production figures are calculated only using single use PET beverage bottles. The
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collection numbers are calculated using the entire PET bale that includes many other types of PET
bottles such as shampoo bottles, conditioner bottles, ketchup bottles, lotion containers, vitamin and
supplement containers, 5 gallon water bottles, 2 liter soda bottles, plastic wine and beer bottles, etc.
This makes the reported recycled rates appear much higher than they actually are.
Often reports claiming an increase in recycling are based on an increase in the poundage of collected
material not an actual increase in the percent of plastic recycled. A recent report claimed a 4% increase
in the recycling of plastic (Johnson J. , 2014), but the report fails to clarify that this is an increase in the
pounds collected for recycling – not an increase in the overall percentage of plastic recycled. Nor does it
include the fact that plastic consumption has increased at a higher rate than the increased rate of
recycling.
When looking at the actual recycling rates, indications are that the overall percentage of plastics being
recycled may be decreasing! The actual recycling rate in the US for plastic was only 9% in 2011 and still
less than 9% in 2013. (EPA, Municipal Solid Waste Generation, Recycling, and Disposal in the United
States, Tables and Figures for 2012) This would seem to indicate that 9% of plastics were
remanufactured into valuable products. But recycling numbers are estimated based on bale weight not
actual material weight. A bale of PET bottles is not only PET bottles, it also includes paper labels, plastic
labels, adhesives, PP and PE caps as well as other incorrectly sorted materials. All of these items are
included in the total weight reported as recycled PET.
Many people aren’t aware that recycle rates are based on municipal waste and not industrial waste.
Why is this important? That PET bale that contained all sorts of other materials is going to be sold to a
processor. Once this bale is sold to a processor, the contaminants and other materials will be removed
and discarded to a landfill. This waste is not considered “municipal waste” as it is now coming from an
industrial site. Industrial waste is not reported in landfill or recycling rates of municipal waste. A
processor could determine that an entire bale of PET is too contaminated to use, send it to a landfill and
that bale would still be reported as having been recycled!
It can be difficult to get a clear picture of where recycling rates are by simply reading media and industry
reports. However, once you understand how the numbers are derived, you can begin to see the true
picture of the current recycling rates. We need to push the recycling industry into reporting recycled
rates based on actual plastic being remanufactured into a new product. Accurate and easily understood
reporting of recycle rates will allow us to determine if our recycling efforts are in fact increasing
recycling rate of plastic or if we are falling short in relation to the growth of plastic production.
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Section 2: Economics of Recycling
Recycling programs in the United States have become an important aspect of waste management. With
the focus on increasing recycling rates it is important to understand that recycling programs can be a
costly method of waste disposal. With the time, money, and energy spent collecting and processing
recycled goods, educational and marketing costs, and subsidies; the price of recycling is much higher
than discarding waste into landfills.
Despite the high costs of recycling, proponents of recycling argue that the environmental and health
benefits of recycling outweigh the costs. Recycling advocates believe that recycling is more than just an
issue of economics and is essential to caring for human health and environmental sustainability. They
argue that recycling is an environmental effort that should be subsidized by the government and taxed
to the consumers and manufacturers. Some believe that any cost – no matter how high – should be paid
to recycle plastic.
This is a philosophy that is great for the recycling industry, but what about from a broader economic
sustainability perspective? To determine the economic sustainability we need to understand the cost of
recycling and how it compares to other methods of waste management.
So, why is recycling so expensive, and what are the actual costs?
In general, recycling is a costly method of waste management as it requires recycling centers to add
specialized trucks and additional employees to collect, transport, and separate recyclable materials. In
New York City, for every ton of recycled goods that a truck delivers to a recycling facility, the city spends
$200 more than it would spend to dispose of that waste into a landfill. There is also the cost of
purchasing, providing and maintaining a variety of recycling containers to residences. Recycling
programs also spend a great deal of resources on continual public relation campaigns explaining to the
public which products are recyclable and which are not.
According to author Harvey Black of the Environmental Health Perspectives Journal, in San Jose,
California “it costs $28 per ton to landfill waste compared with $147 a ton to recycle”. In Atlantic
County, New Jersey, selling recyclable goods brings in $2.45 million. However, the cost of collecting and
sorting these recycled materials plus interest payments on the recycling facility costs the county over $3
million – meaning a net loss of over half a million dollars each year.
In June 2015, one of the largest waste processors, Waste Management, admittedly declared that our
current method of recycling is a “broken model” that is not sustainable. The system does not work
because consumers are demanding more recycling, the processors are bringing in an unburdened
amount of raw material and this recycling is leaving companies with an excess of raw materials and
limited market for the final product. They cannot continue to sell the output for less than the cost of
producing the output - one ton of recycled material can cost anywhere from $65 to $100 to process
(compared with $20 to $40 to dispose the same material in a landfill) and then have a product that’s
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worthless. (Kudialis, 2015).
A case in point, San Francisco's Department of Waste recently calculated it paid $4,000 a ton to recycle
plastic bags. Its resale price for the recycled product? $32. Rivanna Solid Waste Authority, which
operates recycling locations in Virginia, sell their recycled material for $269,000, but the recycling
program cost $634,000 annually, so each year they operate at a loss of $365,000. (Province, 2007) The
promise of environmentalists of a "flourishing recycling market" where reused goods would find ready
buyers "was already a dream 40 years ago and is, unfortunately, still a dream." (Libin, 2009)
States in the US spend over $322 million annually to subsidize recycling, and these recycling costs are
passed to the consumer through trash bills or taxes. One study found that the average cost per
household with curbside recycling was $144 annually; without recycling, the cost of trash disposal was
$119.90. These costs can consume a considerable amount of a city’s budget. For example, Sanford,
Maine, spent $90,990 to recycle waste that it could have safely placed in landfills for $13,365.10.
(Logomasini, 2008)
A large percentage of the cost to recycle is related to the labor costs. In 2011 ISRI reported that the
recycling industry required 459,140 jobs at an average salary of $66,704. That same year, Tellus Institute
projected that to double the recycling rate we would need to add 1.5 million additional jobs. Our current
labor cost for recycling is over $30.5 billion every year; to double our recycling rate we will need to
quadruple the labor expense to $130.5 billion each year!
If we look at the recycling of plastics only, for every 10,000 tons of plastics recycled the Institutes for
Local Self Reliance estimates it will require 103 jobs, whereas it requires only 1 job for the same amount
sent to a landfill. Job creation is often considered beneficial; however in an industry that is not
economically sustainable and requires governmental subsidies, we are doing no more than increasing
the financial burden on society which is not sustainable in the long run.
As we evaluate the economics of recycling, we must compare it to the costs of producing virgin material
(material made from original sources not recycled material). Recycling costs are generally more
expensive than the manufacturing costs of producing virgin materials. Materials, such as plastics, are
more expensive and time consuming to recycle than to produce initially. Thus, it is cost effective to
manufacture virgin plastics rather than recycled plastics, which must undergo collection, transportation,
and sorting costs. This is seen directly in the price of recycled plastic in comparison to virgin plastic,
which is most always less expensive than recycled plastic. This makes the economics even more difficult
because recycled plastic is typically lower quality (strength, purity and color) than virgin plastic.
Manufacturers, brands and consumers don’t want to pay higher price for lower quality.
Another example of the increased cost, but from a different perspective was seen in Seattle when over a
dozen local residents filed suit against the city. The city had hired nine solid waste inspectors to oversee
the residents sorting of materials sent for recycling. The inspectors were sorting through recycle bins
and writing violations and citing fines for residents who incorrectly sorted materials in their recycle bin.
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The residents felt this activity was overly intrusive and filed suit against the city.
Recycling is an expensive venture for any community, primarily because we try to recycle items that
have little value. The data shows that continued recycling of materials with little value will not continue
without additional government subsidies, increased taxes to the consumer, and additional cost to
manufacturers. Any financial burden required to uphold recycling will ultimately be borne by the
individual citizen either through direct taxes or increased product costs.
Many feel that this cost is offset by the environmental benefit of recycling. It is often forgotten that
recycling is a private industry and private industry needs innovation. However, financially propping up
an industry does not spur innovation and economic independence. We must determine the balance
between what is financially supported to assist the growth of the recycling industry for environmental
purposes, and when to pull back and let the market grow naturally.
To determine if the extra cost of recycling is a price worth paying to benefit the environment, we must
look at the environmental impact of recycling.
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Section 3: Environmental Impact of Recycling
Recycling can cost a great deal of money, but that cost can often be justified if the environmental value
is substantial. As is shown previously, recycling programs require additional vehicles which will emit
pollutants, but are there other environmental impacts from the sorting and processing that should be
considered? And if there are other environmental impacts, how does the overall environmental profile
compare to the increased cost?
Overly aggressive residential recycling programs have shown to a community’s environmental goals.
Citywide blue box/bin programs typically mean a whole new fleet of trucks: Calgary added 64 more
diesel-burning rigs retracing the same tracks its garbage trucks did just a few days before implementing
their curbside recycling program, roughly doubling carbon dioxide emissions and other pollutants. The
environmental emissions associated with curbside collection includes significant amounts of carbon
dioxide, carbon monoxide, sulfur dioxide, and other gasses polluting the atmosphere due to the
increased number of trucks on the road. A 2000 study by the London-based environmental group
Friends of the Earth found that collecting waste for recycling emitted 264 more pounds of CO2 than
burying it in a landfill. In 2002, two of Sweden's leading environmental authorities argued that
recycling's benefits were usually undone by the resources required to collect and process it. Other
environmental and social costs found during the study included increased road congestion, litter, and
noise pollution.
The toxic waste released from recycling activities can create long term environmental problems. For
example, recycling plastics creates a waste stream that includes contaminated wastewater and air
emissions. Also, many additives are used in processing and manufacturing plastics such as colorants,
flame retardants, lubricants, and ultraviolet stabilizers. Recycling facilities that do not properly manage
these chemicals may cause health problems for humans, and chemicals that get mixed with rainwater
can also damage nearby biomes and percolate into groundwater. Today, thirteen of the fifty worst
Superfund Sites (hazardous waste sites) are currently or were at one point recycling facilities. These
facilities contain hazardous wastes due to the number of toxic substances utilized and released when
recycling materials.
Rather than focus on the problem creating these sites so that future contamination could be prevented,
on November 29, 1999, President Clinton signed into law the Superfund Recycling Equity Act (SREA).
SREA serves to correct the potential environmental and legal costs of a cleanup that had discouraged
recycling. SREA clarifies that recycling is not disposal, and shipping of material to be recycled is not
arranging for disposal. SREA no longer holds companies who sell scrap for recycling responsible for the
cleanup of contaminated sites when the site's owner or operator has caused the contamination. This
point is brought up to show that there is a loop hole in the system that a recycling facility could use to
avoid responsibility for environmental contamination. Many believe that regulation is overseeing and
controlling possible contaminants and environmental hazards, in this case it is not.
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Overall, the environmental impact of recycling is something to take into consideration. By adding
additional trucks for collection we increase the air emissions, the processing of plastics produces wastes
that may be toxic and uses additional energy. These impacts can be reduced through higher regulation
and restructuring of collection techniques, however this will increase the economic cost of recycling.
The most sensible approach for sustainable recycling is to identify the problematic materials, remove
them from recycling programs and focus our efforts on the plastics that have the best economic and
environmental profile. This will allow the recycling infrastructure an opportunity to maximize the
environmental value of recycling.
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Section 4: Challenges of Recycling
Recyclers are interested in recycling plastics that make economic sense, this worked well when recycling
was limited to PET and HDPE bottles. However with the recent green movement, recycling facilities are
being pushed to accept more and more different types of plastics. Many of these plastics are difficult to
recycle, will not sort using their machinery and have no resale value. The continual push to include more
items in recycling programs is the primary challenge for recycling.
This section will review in detail the challenge with recycling different types of plastics. The information
will help sustainability managers understand why many current products and packaging types are not
recycled. Sustainability managers can also use this information in designing their products and packaging
to more effectively integrate into current recycling infrastructure.
Plastics pose a unique challenge to recycling due to their versatility. If plastics were all one type of
material and the same size/shape, recycling would be much more effective. Unfortunately, there are at
minimum several dozen different types of plastic in today’s waste stream, we have PET, PETG. PE, HDPE,
LDPE, PVC, PS, SAN, nylon, ABS, POM, PLA, EVA, PU and the list continues. Often these plastics look the
same but each type of plastic is a completely different chemical and they are not compatible together.
This means that you cannot mix them. Recycling these plastics requires first separating and sorting them
which can be difficult because they are often visually indistinguishable.
Even a small amount of incorrectly sorted material can be devastating to recycling. For instance; a PET
bottle and a PVC bottle look nearly identical. But, even a small amount of PVC mixed into the PET is
considered severe contamination and will render the entire batch worthless. Similarly, PET and PLA
bottles look the same, but PLA melts at under 200F and PET melts above 400F. In processing PET even a
small amount of PLA will cause issue because the PLA melts during processing and clogs up the
machinery. Again, the entire batch of PET is typically destroyed.
Sometimes sorting the different materials is nearly impossible because many of the finished articles
discarded are created by layering these different types of plastic. This is a growing practice in flexible
films, as seen with juice pouches, bags, and most food packaging films. Cartons are another product that
utilizes multiple layers; although they are marketed as “recyclable” each of these containers is a
complex layering of paper, several types of plastic and metal. None of these materials can be recycled
together so a recycler would need to separate each of these materials. Next time you buy a carton, try
pulling apart each of the layers and you will understand first-hand the complexity.
Additionally, for each different type of plastic, we have different forms; rigid containers, flexible
containers, films, sheets, thermoformed items, injection molded products, roto-molded parts, foamed
plastics, beaded plastic and plastic fibers. Not only are the different types of plastic not able to be
recycled together, the different forms are made from different grades of plastic that cannot be recycled
together either. To create recycled plastic that can be reused, it is required that only the same types and
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forms of plastic be recycled together.
PET is a great example. PET is a type of plastic, but there are many forms of PET. These forms are called
grades. For PET the grade is typically defined by the intrinsic viscosity of the material (the length of the
molecule that makes the plastic). Grades with shorter molecules are typically used to make sheet and
film products, while longer molecules are used to make bottles and very long molecules are used for
monofilament production. Using the wrong grade of PET can result in manufacturing defects and
product failure. This means that with recycling, each of these different grades would need to be
processed separately.
Another example is PE (polyethylene), which is one of the most versatile and widely used plastics. The
polyethylene family of plastics includes; ultra-high molecular weight high-density PE, high-molecular
weight high-density PE, high-density PE, general PE, crosslinked PE, low-density PE, and linear lowdensity PE. Within each of these types of PE, there are different grades that have different melt flows.
Melt flow is how easily the plastic will flow when melted and it is critical to have right when
manufacturing. If the melt flow is wrong, you will have product failure, machine failure and wasted
plastic.
To add to the complexity, recycling processes and systems can only incorporate certain forms and sizes
of materials. There are many materials that are not financially or environmentally beneficial to recycle.
1. Films are lightweight thin plastics such as stretch wrap, shrink-wrap, labels, bags and packaging.
Films are often made from PE, LDPE, HDPE, Nylon, PET or PVC and can include several layers of
different types of plastic that cannot be easily separated or recycled together.
Films and bags cause problems at the reclamation facility as they wrap around sorting
equipment and blow around the facility. Additionally, films are very lightweight so it takes a very
large amount of plastic film to make a bale, meaning that the recycler will spend more on
sorting and processing than they can sell the material for.
2. Foamed materials are often made of PS or PE. Some are extruded foams such as meat trays and
egg cartons while others are expanded beads as is seen with packaging and disposable cups.
These materials are lightweight and brittle causing breakage and difficulty at the sorting facility
and during transportation.
Some foams are chemically modified so they cannot be easily melted and manufactured into
new materials – this makes recycling difficult. Additionally, as with film they are very lightweight
and so unlikely to be economically viable, but unlike film, foamed plastics are primarily air and
take a large amount of space.
3. Small items are another sector that is not typically feasible for recycling. Small items include
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things such as; straws, table service items, single use coffee pods, lids, candy wrappers and most
anything smaller than a beverage bottle. These items are too small for most sorting systems, are
too small to hold together as a bale, and as with both films and foams, contribute very little to
the weight of a bale so are not economical to collect.
4. Contaminated materials are a different type of problem. Contamination can be from the plastic
product itself, during use of the plastic or from contaminants collected during disposal.
Materials can be contaminated with anything from hazardous chemicals which pose a threat to
workers at the facility, to dirt that damages processing equipment, to bacteria/virus risk and
even contamination from materials manufactured as part of the plastic article.
Packaging plastics are usually contaminated from use, think of a bottle that contained bleach
and one that contained ammonia. If these two bottles are baled together during recycling, the
bleach and ammonia can combine creating toxic chloramine gas and liquid hydrazine (an
explosive and toxic liquid). Contamination poses a serious risk to recycling many materials.
5. Complex materials are very common in the waste stream. These are products made from layers
of different types of materials. The layers can be different types of plastic, or they can include
metals, paper and rubber. This is very common seen in cartons for food packaging, electronics,
pouches, furniture, automotive materials, batteries and toys. These types of products are some
of the most common ones in municipal waste and separating these materials is very energy
intensive and can require the use of harsh chemicals, both of which make attempting to recycle
these materials ineffective.
6. Colors can cause a problem with recycling because it makes it more difficult to distinguish
between different types of plastic and lowers the quality of the plastic. Color in plastic becomes
a permanent feature and there is no way to remove color when recycling. Take a stroll down the
grocery aisle and notice the different colors of plastic. Mixing these colors in recycling is like
mixing a pallet of paints – brownish-green-gray plastic.
The challenge in recycling extends beyond the types of plastic, their forms and contaminants. There is a
general misconception of closed loop recycling – a belief that plastic can be recycled over and over again
indefinitely. This is not the reality of plastics recycling. To recycle plastic it must not only be collected,
sorted, decontaminated and ground into flake; it must also be melted and remanufactured into a new
product.
Each time plastic is melted it will degrade the polymer chain (meaning the plastic becomes weaker and
more brittle), after 3-4 melt cycles the plastic becomes virtually unusable and will be discarded – into a
landfill. This is the reason many products contain only a portion of recycled content – they need virgin
plastic to overcome the degraded state of the recycled material.
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Most plastics however are not remanufactured into the same type of product or a product that has a
high chance of being recycled. Most often, recycled plastic is actually down-cycled (made into less
valuable products that are not recyclable). This is seen when plastic bottles are recycled into clothing,
after the clothing is worn the plastic fibers will not be recycled and will be thrown in the landfill. This
prevents the option of closed loop recycling systems and instead simply extends the life span slightly
and delays the inevitable disposal into the landfill.
Another challenge for plastics recycling is the current trend of “reducing” plastic use. This is part of the
“Reduce, reuse, recycle” mantra. Most often this reduction comes from “light-weighting” packaging and
products by making the same item thinner and with less plastic (think of how water bottles have
changed over the past 5 years). A water bottle has reduced plastic use by nearly 50% in the past few
years, meaning that recyclers must now collect twice the amount of bottles for the same weight. Since
recycled material is sold by weight, each bottle is only half as valuable as it was a few years ago.
A more recent trend is changing from rigid packaging to pouches and films. This approach is even more
problematic for recycling as pouches and films are most often multi-layer to compensate for the thinner
material and multi-layer film is not recyclable because the different types of material used in the
multilayer are not compatible and cannot be recycled together or separated. This is another revenue
loss for the recycler. Even if the film is a single material, most recycling systems will not accept it,
resulting in all of these films and pouches being diverted directly to the landfill.
From a product perspective, many brands claim the desire to produce “recyclable” products. They make
changes in their product or packaging in the desire to make it more recyclable without understanding
the full dynamics of the collection, sorting and processing inherent in recycling. Brand owners believe
they can make their package recyclable by converting to a plastic that is recycled. Not only is this not
true, it is misleading to the public when the brand promotes their product as recyclable when it is not
going to be recycled.
For example, there is a single use coffee pod made of multi-layer material which has received significant
negative exposure in the media because the pods are not recyclable. Recently, the manufacturer of
these pods announced they are changing the pod to polypropylene, a “recyclable” plastic as a more
environmental option. However, these claims fall short. The reality is that a coffee pod will not be
recycled regardless of the resin it is manufactured from – the size of the product is the limiting factor.
Recyclers that receive these pods during curbside collection will not process them and the pods will be
sent to a landfill. Even if a recycling facility would accept a large shipment of these pods, there is not an
economical or environmental means to collect these items separately. Ultimately these coffee pods will
be sent to a landfill. This is completely misleading to consumers who do not understand the limitations
of recycling.
If a brand is truly interested in making their product recyclable, they need to use materials and forms
that are currently recycled. This means changing their packaging to PET or HDPE rigid containers only.
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They would not use any colors, processing aids or barrier materials in the plastic. They would avoid the
use of labels, caps and other items that will not be recycled and could hinder the recycling of their
product. They would not use any films, bags, pouches, foams or any other materials or forms that would
limit the recyclability.
Changing packaging to completely integrate with recycling can be very limiting to a brand because the
look, feel and quality of their product are often controlled by the packaging. And it may be more
expensive, use more plastic and still not ensure it gets recycled – however when brands are willing to do
all of these things, they can honestly market their product as recyclable. Any deviation from this and
they are simply using the term “recyclable” as a marketing tool. At best, this approach is referred to as
“greenwashing”.
The Association of Postconsumer Plastic Recyclers (APR) publishes a technical guide for designing
products that will integrate most effectively with current recycling methods. While not completely
inclusive as it can overlook new technologies, the APR guide can be a good tool to use when evaluating
the design of packaging. Currently the guide provides direction on subjects such as; caps/closures,
labels/inks, colorants/additives and material layers as they relate to PET and HDPE bottes. This guide
can be found at the APR website: www.plasticsrecycling.org.
There are many challenges to recycling materials in a sustainable way. Plastics come in many different
types and forms; each of these requires separation from the other before recycling. Separating these
plastics is expensive and sometimes impossible. If brands want to ensure their products are recycled
they will need to redesign their products and packaging in ways that may not protect the product
effectively and will cost more. While some brand owners claim to have recyclable materials, they do not
ensure they are actually recycled or integrate into the existing processes of recycling. Brands should not
market their product as “recyclable” until that product will actually be recycled.
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Section 5: Sustainability with Recycling
Recycling is an important part of a sustainable waste management system. A system that recognizes
some portions of our waste are most efficiently recycled, some are most efficiently placed in landfills,
some should be burned in incinerators, and other materials should be composted. The key is finding the
mix of options that conserves the most resources, while protecting the environment. Each option
represents its costs to society: the value of the water, energy, land, labor, and other resources that the
disposal option requires.
Using numbers that are reported by the EPA, less than 9% of all plastics are being recycled. Increasing
the recycling rate of plastics to even 20% will require millions of dollars in public funding and a change in
the way products are manufactured and packaged. It will also require recyclers to approach their
business from an environmental focus rather than an economic one. With these changes, we can
increase our plastic recycling rates, but it is naïve to expect that we should recycle all plastics.
When looking specifically at plastics, there are a few materials that are currently recycled effectively;
clear PET beverage bottles and HDPE bottles. One reason it's so hard to increase recycle rates is because
we're already recycling the most valuable and accessible items: bottles. The rest of the waste is hard to
collect, difficult to process, requires greater resources and has almost no value. (Porter, Playing the
game to meet the 50% recycling law, 1997)
The diversity of plastics in the waste stream is exasperated by modern requirements for product safety
and preservation. As manufacturers and brands design packaging to better preserve and protect
products it requires more diverse types of packaging. This creates thousands of items that are not only a
challenge to recycle but are available in such small quantities that they are not feasible to recycle.
If brands want to have their products or product packaging recycled, they must first understand the
processes and business of recycling so they can design products and packaging that integrate with
recycling. This will mean making packaging out of materials that are currently recycled effectively and in
a form that will be recycled. Specifically, they will use only clear PET or HDPE bottles. They will avoid
adding any labels or caps that are not easily removed and they will not use multi-layering of plastics in
their bottles.
For many products packaging with bottles may not be possible and changing a product or packaging
based solely on the ability to recycle the item will have unintended consequences. Sustainability
managers must balance the cost and performance of their plastic with the disposal environment they
intend for their products. Not all packaging performs as needed when it is the type and form of plastic
most recycled; for these products, designing for alternative disposal methods is appropriate.
Brands can also assist recycling by using recycled content in their products. This supports the resale
value of recycled material and will result in higher demand for the recycling of those specific products.
This does not directly impact the recyclability of the finished product but it does support the recycling
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industry and indirectly will encourage higher percentages of recycling.
Sustainability with recycling will require the recycling industry to step up to the plate and approach
recycling from a sustainability perspective rather than only a commercial business perspective. This will
involve working with manufacturers and the community to identify which materials are beneficial to
recycle and focusing on those materials. This may mean pushing back on the idea of including all plastics
in their collections, and it may involve calling out products that incorrectly claim recyclability because
they are in a form that is not recyclable.
To have recycling sustainable, we must understand that not all materials should or can be recycled. We
must understand that the decision as to what materials are collected for recycling can determine if the
program is beneficial. Too often it is assumed that if recycling aluminum, copper, paper and select other
materials is beneficial, that same benefit will be realized with all materials. It is also assumed that
recycling is limited to the collection, separation and reprocessing of materials into similar products. This
limited perspective blinds us to the true impacts of wide spectrum recycling initiatives.
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Chapter 3: Incineration of Plastic
The third most common method of waste disposal for plastics is incineration; this is a waste treatment
process that involves thermal degradation of waste materials. Incineration is widely used throughout
Europe and Japan, as a method to avoid landfilling of materials and to capture the energy value of the
waste. In this section several types of incineration technologies are included; combustion, gasification
and pyrolysis.
Combustion is the simplest and most common form of incineration as it is simple burning of waste.
Combustion can accommodate mixed waste, although for health, safety and environmental purposes
hazardous wastes should be removed prior to combustion. Combustion can be used only to reduce the
volume of waste, or the resulting heat from combustion can be harnessed as an energy source. From a
sustainability perspective, it is always best to capture the energy value during incineration rather than
simply burning the materials.
Combustion is the most common form of incineration worldwide. It is popular in Japan, Denmark and
Sweden where the combustion facility also captures the energy value of the waste. In Denmark, waste
combustion energy accounted for 4.8% of the country’s total electric usage and 13.7% of their domestic
heat consumption. (Danish Energy Authority, 2007)
Plasma gasification is a new method to thermally treat waste materials that is not yet used in
commercial applications. It involves using a plasma torch to heat the waste to temperatures up to
25,000F so that the waste instead of burning is vaporized. Basically, the heat is so high that it breaks the
molecular bonds in the materials and the complex molecules are separated into individual atoms. The
end goal with plasma gasification is a combustible gas called Syngas which can be used for fuel.
(Kalinenko, Kuznetsov, Levitsky, Messerle, & al, 1993)
Pyrolysis is another new technology that is not used often commercially. Pyrolysis uses high heat (not as
high as plasma gasification) to transform the waste materials; however it is more often used with preseparated waste rather than mixed waste. Plastics that have been separated from other waste can be
converted to a diesel like fuel through pyrolysis. This technology is expected to work well for plastics
such as polyethylene and PS, but other plastics may cause difficulty. PET and PVC are not suitable for
pyrolysis. Therefore it will be necessary for plastics being sent for pyrolysis to be separated similar to
separation for recycling. (Ricardo - AEA, 2013)
Incineration of waste materials is a common practice in many countries throughout the world. In some
countries incineration is comparable to recycling in regards to desirability and the materials incinerated
are included in recycling figures. However, there are also those who feel incineration should not be
advocated and that the environmental and economic impact of incineration outweighs the value.
Let’s consider the details of incineration.
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Section 1: Understanding Incineration Rates
The amount of waste sent to incineration varies significantly by region. In certain European countries,
incineration rates of waste can be as high as 50%. The US incinerates significantly less, at 10% of
municipal solid waste. (EPA, Municipal Solid Waste Generation, Recycling, and Disposal in the United
States, Tables and Figures for 2012).
When reporting incineration rates, some countries include the figures as part of their recycling numbers,
where other countries separate combustion into a separate category. Some reports do not specify if the
combustion also included energy recovery which can be an important factor in evaluating the
environmental value of incineration.
Obtaining the incineration rates for different regions can involve parsing data from several sources and
possibly separating the incineration with energy recovery from that of incineration without energy
recovery. Unfortunately, incineration figures are not readily available and it will require some effort to
dig through numbers in order to understand how much of your company’s waste is actually being
disposed of in an incineration facility.
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Section 2: Economics of Incineration
The cost to incinerate waste will be heavily dependent on the incineration technology utilized and the
air emission requirements implemented. On average, municipal solid waste (MSW) incineration plants
tend to be among the most expensive solid waste management options when environmental emissions
are managed, even when the value of the resulting energy is considered. The implementation and
operation of incinerators will require public funding or increased costs of waste disposal fees. (The
World Bank, 1999)
Waste incineration facilities are expensive because they require highly skilled personnel and careful
maintenance. The capital costs to build incineration facilities can be very high and the operation of the
facility can also provide difficulty in economic sustainability. Combustion tends to be the least expensive
from a capital and operational perspective, whereas gasification and pyrolysis are significantly more
expensive.
Incineration through combustion can be less costly than recycling for many materials, including mixed
plastics. Primarily this is because the plastic does not require any additional collection trucks, separation
or processing prior to combustion. However, from a strictly financial perspective the biodegradation of
mixed plastics in landfills is the least costly option.
Gasification and pyrolysis are both promising technologies for the conversion of plastic to fuel; however
at this time there is no large scale commercial gasification or pyrolysis facilities due to the high cost, so
these technologies are not covered here.
From an economic perspective, incineration of waste can be an expensive option for waste disposal and
the costs to implement incineration should be weighed carefully against other waste disposal options.
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Section 3: Environmental Impact of Incineration
Incineration of waste materials is a controversial subject from an environmental perspective. There are
arguments that incineration is beneficial and other arguments that it is detrimental. Often the
arguments from both sides have validity and sometimes they are referring to different technologies of
incineration. The environmental impacts of incineration very significantly by the type of incineration and
the control measures used at the facility to prevent pollutants from being released into environment.
It is important to note that gasification and pyrolysis both have the potential for a better environmental
footprint over combustion incineration. The intense heat used in gasification and pyrolysis removes
much of the toxins and results in fewer emissions. Combustion is the only form of incineration used on a
commercial scale so the environmental impact discussed here is considered only from combustion
incineration perspective.
The environmental effects of combustion are related to the feedstock. Most often combustion involves
mixed waste rather than sorted materials. The combustion of mixed waste can create toxic ash that
must be disposed of in a controlled hazardous landfill site. (Grundon, 2004) While the ash is an area of
concern, the highest environmental risks are due to the emissions during combustion. (The World Bank,
1999)
Combustion produces dioxin and furan emissions that unless controlled pose health risks, most wellconstructed and maintained facilities will filter the air to remove these before releasing the gas.
Filtering can remove these toxins, but other toxic materials such as vanadium, manganese, chromium,
nickel, arsenic, mercury, lead and cadmium can be more difficult to remove through filtering. And even
after filtration, ultra-fine particles remain that are released into the atmosphere. (Godfrey, 2009)
These toxins and ultra-fine particles are shown to accumulate in the human body causing cancer, birth
defects, asthma, emotional and behavioral problems and death. These health impacts have resulted in
the Paris Appeal of 2004, 2006 and 2008 in which hundreds of scientists, 200,000 doctors, 68
international experts, the International Society of Doctors for the Environment and the medical
organizations of 25 EU member states representing 2 million doctors, called for a moratorium on the
building of any new incinerators in Europe. (Godfrey, 2009)
Often combustion is considered a good option to reduce the volume of waste going into landfills.
However reports show that at least 25% of the mass entering a combustion facility comes out as ash
volume and is sent to landfills. (Godfrey, 2009)
Overall there are environmental impacts to incineration that must be considered when evaluating the
sustainability of incineration and the most common form of incineration is producing significant
environmental impacts.
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Section 4: Challenges of Incineration
Beyond the environmental and economic impacts of incineration, there are additional challenges to
incinerating plastics. Incineration can take mixed waste just as it is provided from a consumer’s trash but
this mixed waste will produce additional toxins. There also is a social hurdle as some believe that
widespread incineration will hinder the progress of recycling.
Another challenge is when combustion facilities take in mixed waste, but some of the waste will be of
little energy value and may have high moisture content or may be toxic. Both of these can reduce the
effectiveness of the system. Ideally, materials entering the combustion facility would be high energy
items such as plastics and paper. These are also the items that if separated from other waste are most
often recycled. But, if recycling and incineration both require sorting and processing of the same
materials than which is the best option from an environmental and economic perspective? This will
create a struggle between increasing recycling and increasing the efficiency of combustion.
There are concerns that using combustion as a method of landfill diversion can decrease the desire to
recycle materials. The concern is that if the combustion of mixed plastics is less expensive than recycling
mixed plastics there will be more incentive to incinerate the plastic than to recycle it. This concern is
increased in areas where combustion incineration is included in the reports of recycled plastics.
(Seltenrich, Incineration Versus Recycling: In Europe, A Debate Over Trash, 2013)
There is also social movement to ban the use of combustion incineration due to the potential health
hazards. In 2009 the Paris Appeal requested a moratorium on any new incineration facilities (Godfrey,
2009). Some regions have banned the incineration of waste, including gasification and pyrolysis. In 2009
Hidalgo was the 4th Mexican state to ban the use of incinerators for municipal solid waste. (Tamborrell,
2009) That same year, incineration was banned in the Philippines after 9 years of community pressure
stating the health and environmental impacts of incineration were too detrimental.
(Farmaciaannunziata, 2009) Incineration bans have been proposed in other areas such as Rhode Island,
Utah, New Zealand, Maryland, UK, and the greater EU.
Overall, there are challenges that must be addressed if incineration is to be a sustainable method for
handling some of our waste materials. These challenges are environmental, health, economic and social.
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Section 5: Sustainability with Incineration
Sustainability with incineration is primarily a community agenda, meaning that sustainability managers
will have little influence over how incineration is managed. There is little action that a company can take
in regards to incineration and the impact of plastics on incineration will not be determined by the
product or packaging design.
Primarily, sustainability managers only control the design of their products and packaging. That design
should include understanding how the materials will affect the disposal environment. While
sustainability managers cannot control if their products and packaging will be landfilled, recycled or
incinerated, they can ensure that they use materials that will biodegrade in landfills, are valuable if
recycled and have energy value if incinerated.
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Chapter 4: Composting of Plastic
Composting is a disposal method primarily for food and yard. With a growing focus in this area, there
have been new plastics developed that are specifically designed to be commercially composted
alongside food waste. The concept of composting these plastics is to produce a nutrient rich soil
amendment that can be used for enriching depleted soil in gardening and farming. Although composting
is a general term that relates to aerobic biodegradation, for purposes of this section we are referring to
industrial composting only.
Compostable plastics have the potential to be a great part of an overall sustainable plastic strategy.
Sustainability managers looking for product solutions that relate to composting may find that
compostable plastics provide a beneficial alternative to traditional plastics. So, how can we make
compostable plastics more sustainable?
What are Compostable Plastics?
Compostable plastics are not the same as traditional plastics. This may seem obvious to the polymer
chemists out there, but for everyone else it is easy to think of plastics as being all the same. Each type of
plastic has a very unique molecular structure, meaning they have very different characteristics. They will
melt at different temperatures; some are hard and brittle while others are flexible and soft; plastics can
be made from fossil fuel or out of plants such as corn, sugar cane and potatoes. Some plastics are made
in nature while others are only created synthetically. Even more complex is that some plastics are
inherently biodegradable while others are not and their biodegradability does not depend on if they are
made from plants or fossil fuels.
Note: There is sometimes confusion regarding the differences between compostable,
biodegradable, renewable and traditional plastics. To clarify this, traditional plastics are
made from fossil based plant resources while bio-based/renewable plastics are made
from recently living plant resources. Both of these refer only to what type of resource
was used to create the plastic and most types of plastic can be made from either source.
Biodegradable and compostable refer to how and where a plastic will biodegrade.
Compostable plastics are those that will biodegrade in an industrial compost process
within the time required for commercial resale of the final compost. Biodegradable
plastics are plastics that will decompose through the action of naturally occurring living
organisms, this can occur in many different environments such as; native soil, home
compost, industrial compost, landfill, ocean, etc. Both biodegradable and compostable
plastics can be manufactured from either renewable or fossil based sources.
A popular compostable plastic (PLA) is made from corn rather than petroleum. This plastic is not as
durable as traditional plastics and melts at very low temperatures (think of your car in the summer kind
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of heat). PLA doesn’t have the same barrier properties, which means that they are not air and water
tight as provided from traditional plastic. Additionally, the use of PLA can require more plastic than
traditional plastic to make the same item.
However, compostable plastics also provide the opportunity to integrate plastics into composting of
food waste which can be beneficial. In doing this, plastics need not be sorted from the food waste and
this can make composting a simpler solution for commercial facilities that have large amounts of food
waste. In commercial facilities it can be difficult to separate plastic from food waste, and in this scenario
compostable plastic can be a good option.
Because compostable plastics are so much different than traditional plastics, they cannot be comingled
in the recycle stream and they must be separated. Many of these plastics look and feel the same as
traditional plastic so they are put in the recycle bin with traditional plastic. If these plastics are sent to a
recycling facility they can damage equipment or make entire batches of recycled plastic worthless from
contamination and result in it all being landfilled. In short, compostable plastics are not recyclable with
traditional plastics.
Some facilities have the ability to sort out the valuable plastics and prevent the contamination of
compostable plastics. Once sorted, these compostable plastics are not sent to a compost facility but are
sent to the landfill where they are not designed to biodegrade.
Compostable plastics are different than traditional plastics, they are manufactured differently, they
perform differently and they should be disposed of differently. Each of these factors is important to
understand the overall sustainability profile of compostable plastics.
The Environmental Impact of Creating Renewable Plastics
Creating any product has an environmental impact; this includes both traditional plastics and
compostable plastics. This section is going to specifically focus on renewable based plastics primarily
because some feel that plastics made from plants are inherently better for the environment. Renewable
plastics have environmental impacts; the key is to know what environmental impacts are involved so
they can be assessed against traditional plastics.
Compostable plastics can be made from fossil fuels; however the most utilized compostable plastics are
made from corn, potatoes and sugarcane. These plastics are often marketed more environmentally
sustainable because they are renewable and compostable. The concept in using plants is that it would
give the plastic a better environmental profile than it would have if the plastic were made from
petroleum. We can make assumptions as to the environmental value, but to achieve sustainability we
must evaluate the data.
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First, we will take a look at PHA (Polyhydroxyalkanoate), a compostable polymer produced by bacterial
fermentation of sugar or fat. There is widespread belief that PHAs are a sustainable alternative to
traditional plastics because they are made from sugar and are biodegradable. However, in considering
the full impact of making PHA we find that PHA fermentation process consumes 22% more steam, 19times more electricity, and 7-times more water than it would to produce the same amount of traditional
plastic (specifically polystyrene). Producing PHA consumes significantly more energy, releases more net
greenhouse gases than conventional petrochemical polymer production.
Note: Even when some of the data seems similar, it is necessary to evaluate carefully. For
instance, with PHA, reports often state that the consumption of fossil fuel is similar to
the amount required to produce polystyrene. It takes 2.39 kg of fossil fuel to produce 1
kg of PHAs, and 2.26 kg of fossil fuel to produce an equal amount of polystyrene. This
may seem like they are very similar, but what is not disclosed is that PHA production
requires the combustion of the entire 2.39 kg for energy production, whereas
polystyrene production combusts only 1 kg of the 2.26 kg fossil fuel and the remainder is
the actual plastic. (The energy consumption estimates used in the analysis above are
very conservative and far below those of other researchers who have assigned energy
requirements to PHA fermentation processes that were 57% and 467% greater than
those used in the present analysis for electricity and steam, respectively. If their values
were used, the net effect would be fairly drastic, resulting in an overall fossil fuel
consumption of 3.73 kg per kilogram of PHA). (Gernross, 1999)
When we look at another popular plastic, poly-lactic acid (PLA) which is made from corn (most often
referred to as “corn plastic”) the overall sustainability comes into question again. A recent report by
NatureWorks, a primary producer of PLA, clearly outlines the resources required and waste created to
produce PLA.
To produce one kilogram of PLA plastic it requires 67MJ of energy, the equivalent of 1.0168kg of energy
mass. But the resources required to manufacture PLA go far beyond the energy; it also requires 48kg of
water and an additional 2.3kg of other raw material such as fertilizers and fossil resources. In evaluating
the waste, each kilogram of PLA produces .27kg of solid waste, almost a kilogram of water and air toxins
and 1.3kg of CO2. Add up all these resources and waste and we find that to manufacture 1kg of PLA will
require 51kg of resources and produce 2.5kg of waste! A system cannot be sustainable when the inputs
are 51 times greater than the product itself and the wastes are over twice. (Erwin Vink, 2010)
Researchers at the University of Pittsburg found that biopolymers are among the most prolific polluters
during their production. This is primarily due to the impacts of farming (agricultural fertilizers and
pesticides, extensive land use for farming) and the intense chemical processing needed to convert plants
into plastic. The cultivation of corn, the primary crop for plant based plastics, uses more nitrogen
fertilizer, more herbicides and more insecticides than any other US crop; exhibiting the maximum
contribution to water eutrophication (what happens when over fertilized water can no longer support
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life). It is clear that plant based plastics are not necessarily better than traditional ones. (Kelly, 2010)
Not only are plant based plastics possibly not better than traditional plastics, the environmental harm
they create may be far more critical than that caused by traditional plastics. In Brazil, sugar cane is
farmed to produce plant based plastics from ethanol. These farmlands are not only destroying vast areas
of rain forests, but the burning of sugar cane prior to harvest produces a huge amount of emissions (air
pollution). Epidemiological studies suggest that exposure to these emissions results in respiratory
disease. The radiative forcing of the emissions may also have significant regional climate impacts. And
according to researchers, climate change may be the least of our concerns. (C-C Tsao, 2011)
Earlier this year, a group of nearly two dozen researchers representing countries from around the world
(Sweden, Australia, Denmark, Germany, UK, USA, Canada, South Africa, and Kenya) released a study
identifying the most critical areas of concern regarding the environment. (Will Steffen, 2015) This study
provides a method of prioritizing environmental impacts so that decisions are based on the most
important and critical areas.
Figure 7: Planetary boundaries showing the highest areas of concern are nitrogen, phosphorous, genetic diversity all of which
are in the zone of certain danger. Land system change is nearing the danger zone. All of these criteria are directly related to
farming. (Will Stephen, 2015)
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This study categorizes areas of environmental impact such as climate change, fresh water usage,
biosphere integrity, land-system change, and ozone depletion. The purpose of this study was to assist
societies with making decisions that will allow life on this planet to continue by addressing areas that are
nearing tipping points of irreversible damage.
The results of this study showed that we are damaging the planet in ways that are worse than climate
change. While we all hear about climate change and many sustainability programs are based on carbon
footprint to reduce the contribution to climate change, it is seldom we hear about biosphere integrity,
land-system change, phosphorous and nitrogen pollution or the importance of genetically unique
materials; and yet these were found to be critical areas where we are destroying the resiliency of the
earth and its ability to support life.
Genetically unique material means the variances in genetics both between different species of plants
and animals as well as genetic diversity within species. This genetic diversity is the information bank that
ultimately allows life to adapt and co-evolve with changing conditions. Genetic diversity provides the
long-term capacity of the biosphere to persist under and adapt to abrupt and gradual abiotic change.
The importance of diversity is seen first-hand in farming when there are droughts and disease that
affects a specific crop and the effect is devastating. Modern farming minimizes the genetic diversity by
destroying areas of diversity and replacing it with identical crops. This not only creates a system with
very little resilience, but is also destroying the ability of the earth as a whole to adapt.
Farming not only reduces the genetic diversity but also is the primary contributor to nitrogen (N) and
phosphorous (P) pollution. These fertilizers add N and P to depleted soil to assist plant growth, but also
put excessive nitrogen and phosphorous in the water runoff from irrigating crops. These fertilizers are
devastating to our water and ocean systems because nitrogen and phosphorous cause water
eutrophication, or the inability of bodies of water to support life.
Another direct impact toward sustainability is land-system change. This is the conversion of the three
primary forest biomes (tropical, temperate and boreal), which control land surface-climate coupling
(exchange of energy, water and momentum between the land surface and the atmosphere) and genetic
diversity, to cropland. Our current rate of forest destruction is unprecedented, especially in tropical
regions which have the largest affect to climate change when they are converted to non-forest systems.
While land-system change is not yet in the high risk range, it will transgress this barrier shortly should
we continue to expand farmland for non-food uses.
While this study clearly identifies risk levels of several categories, it also identified new areas of concern
that do not yet have known risk levels. One of these is called “novel entities”. Novel entities are human
developed substances and organisms for which we do not yet know the long term effects. Entities of
concern are determined by the ability of the entity to persist in the environment, they can spread within
the environment and they have a potential impact on the earth processes or life systems. This includes
genetically engineered species released into the environment which are not naturally occurring. These
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global-scale experiments on the genetic codes of life are being performed on this planet through
genetically modified crops (corn is a primary one that is used for plastics) and we have no concept of the
long term danger.
The genetic diversity and nitrogen/phosphorous levels on this planet are currently beyond the tipping
point of irreversible damage and land-use change is close behind. These areas of damage are almost
solely due to farming. These are areas that are no longer in a zone of uncertainty as we still see with
climate change; the current damage to genetic diversity and the N/P levels are a clear and present
danger to life on this planet. Land system change will exceed the high risk zone very shortly. We are also
increasing the use of genetically engineered crops that are disrupting the natural genetics of this planet.
With this in mind, does it make sense from an environmental sustainability perspective to increase
farming to support plastics production at the risk of planetary stability?
The impact of farming for plastics cannot be taken lightly, however this does not mean that using fossil
fuel for plastics is the answer. Ideally, there should be a transition away from fossil fuels and toward
sustainable sources for materials. Perhaps, farming just isn’t the right direction.
With this perspective, there are some compostable plastics made from sources that can avoid excessive
farming. One of these is thermoplastic starch based plastics such as ENSO RENEW that are made from
potato starch. While potatoes are farmed, and the farming itself has the impacts described above, ENSO
RENEW is made from the starch that is leftover after potato processing. In this way, the use of the starch
does not increase the impact of farming, and it uses a material that may otherwise become waste.
Another interesting advancement that may prove to be a beneficial solution is in using methane
produced in landfills and dairies as a source material for plastics. BASF has plans to open a methane-topropylene manufacturing plant in 2019. Total Petrochemicals started their methane-to-propylene plant
back in 2010 and there are others doing the same, such as UOP and Air Liquid. (Chang, 2014) Using
methane to create plastics will be most effective environmentally if that methane is obtained from
landfill gas or dairy farms. In this way, the source for the plastic is again a waste material that is being
utilized and it has the benefit of reducing greenhouse gases that may otherwise be emitted.
There is also work in progress to make plastics from algae. Algae are unique in that they can use waste
water and CO2 from industrial facilities and use these as a food source to grow. Just add sunlight and
you have everything needed to grow algae. Some of the processes to grow algae include vertical
systems that occupy minimal land space and other systems use open ponds that can integrate into more
natural type habitats.
All of the data in this section is not to discourage the movement toward bio-based plastics, it is designed
to shed light on the negative impacts that should be considered when selecting the type of plastic to
use. Any plastic will have impacts, but we should prioritize which impacts are the highest priorities.
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Section 1: Understanding Composting Rates
Compostable plastics have been in existence for some time but the commercialization of compostable
plastics is fairly new. There is currently no infrastructure in place that allows for the inclusion of plastics
in composting on a broad scale and as such, there are no reporting mechanisms to provide information
as to how much, if any, compostable plastics are entering industrial compost facilities.
Over the last handful of years several studies have been performed by industrial compost facilities to
evaluate the effectiveness of compostable plastics in industrial compost operations. The results of these
studies were mixed and as such the current approach of most industrial compost facilities is not to
accept compostable plastics.
At this time we are unable to provide information on how much, if any, plastic is actually being disposed
through industrial composting.
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Section 2: Economics of Composting
Economic factors must also be considered in a full sustainability profile. Implementing and maintaining a
commercial composting program requires capital expenditures due to the collection, storage, processing
and post–processing storage of compost. These higher operation costs can be overcome if the final
product can be sold at a profit. In some regions the final compost is given for free or even used as daily
cover in landfills. Most often commercial compost facilities are not profitable as the overhead is higher
than the resale value.
Collecting material for commercial composting is expensive as it requires separate trucks travelling long
distances to collect small amounts. The coalition for Resource Recovery found the cost of collecting
waste for commercial composting in a city can be as high as $233 per ton. It costs twice as much to
transport the material to compost as it does to landfill as there must be a separate truck to collect the
material and that truck will travel more miles to collect the same amount of waste, which means
increased fuel cost, more vehicle maintenance and more wages paid to collect the same amount of
material. (Matt de la Houssaye)
In Pennsylvania, Upper Mt. Bethel Township was considering implementing a commercial compost
program for yard trimmings. The assessment found that it would cost the township over $100K each
year to operate the compost program – more if they paid the workers anything over minimum wage.
(Environmental Resources Associates) This is just operational costs and does not include the extra cost
to collect the material for composting. If we include the increased collection cost above, it would add an
additional $73K of expense each year, totaling nearly $175K annually to have commercial composting in
this township.
Operators of composting systems can overlook critical processes and cost factors. As a result,
communities might adopt bad composting systems that produce strong, unpleasant odors, create toxic
compost that has limited/no use, or that require much more investment than initially quoted. One of
the primary contributions to the failure of organic composting programs is the lack of resell value and
demand for the resulting compost. For example, in Virginia the compost program is operated by
Environmental Solutions, a contract for that service costs $450,000– and there is no compost revenue.
(Province, 2007)
Failure of commercial compost programs is an expensive situation for municipalities. Failure of a large
composting system typically involves loss of about $30 million, according to Professor Melvin S. Finstein
of Rutgers University. Notable failures include the Agripost facility in Dade County, Florida; the
Reidel/Dano facility in Portland, Oregon; the Pembroke Pines facility in Florida; and the Pigeon Point
facility in Delaware which operated for almost 10 years but was recently closed because of odors.
Most often, commercial composting is subsidized by the local community as an environmental service
and method to obtain federal recycling guidelines rather than as an economically sustainable activity.
The profitability of commercial compost facilities is difficult as the overhead is often higher than the
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resale value.
To make commercial composting economically sustainable markets should be developed or found that
will bear the increased cost by purchasing the resulting compost, this is going to be directly tied to the
quality of the compost. When not economically viable, residents, businesses and public/private entities
will need to bear the burden of commercial composting expenditures.
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Section 3: Environmental Impact of Composting
Industrial composting sounds like such a natural process, at first glance one may believe that it is the
same process as happens in nature. Material biodegrades into great soil, new plants grow from the soil
and the cycle of nature continues. With that perspective it would appear that adding plastics into the
system would be a great idea. An evaluation of the effectiveness of composting plastics must include
consideration of the economic impact, consumer impact and environmental impact. (Food, 1996) So,
what are the environmental impacts of industrial composting?
One of the benefits cited for composting relates to reductions in carbon footprint. The environmental
impact of composting from a greenhouse gas (GHG) perspective is most often due to the reduction of
methane that would have otherwise been produced if the material was in a landfill. However, if a
compost system is not strictly controlled, the decaying material will often still produce methane. Even
well maintained compost will produce greenhouse gases.
While methane is typically reduced, the amount of nitric oxide can be higher with composting than with
landfilling. Nitric oxide is created in compost due to the intense microbial activity and nitric oxide is 240
times more harmful than carbon dioxide (CO2) in contributing to global warming. Nitric oxide is also
stable in the environment, meaning it will last for a long time, and contributes to the destruction of the
ozone. (Barton & Atwater, 2002) (Food, 1996)
The greenhouse gas impact will depend on the type of waste composted. The end result of
biodegradation is primarily CO2. Nearly 50% of organic waste will convert fairly rapidly to CO2; this is
considered a fast to moderate degrading material. The other half will remain as carbon in the soil and
slowly complete the biodegradation over several years to decades. This balance of fast and slow
degrading portions creates valuable nutritious soil that is carbon rich can retain moisture and support
plant growth, while also limiting the carbon emissions.
When comparing emissions from compost and landfilling, studies indicate the net GHG emissions from
composting are lower than landfilling for food discards, but the opposite is true for yard trimmings.
(EPA, Solid Waste Management and Greenhouse Gases, 2006) This is primarily due to the rapid
degradation of food waste in landfills (meaning rapid conversion to methane) and the high percent of
yard waste that decomposes slowly in compost - leaving carbon in the soil (humus). Slow degrading
material represents approximately 52 percent of carbon in compost (EPA, Solid Waste Management and
Greenhouse Gases, 2006). The slower degrading material provides the reduction in carbon footprint as
well as the value of nutrients in the soil.
If we consider plastics in the compost environment, with compostable plastics there is no slow
degrading portion as compost standards for plastic require a minimum 90% conversion to CO2 within
180 days (ASTM D6400), this prevents slower degrading portions of carbon remaining as humus. The
value proposition for plastic materials is not the same as it is for food waste because less than 10% of
the carbon can remain in the soil and the remaining 90% is required to convert rapidly to greenhouse
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gas. But, how does composting compare with modern landfilling from an environmental perspective,
and which is the most beneficial route for plastic disposal?
There have been a number of studies conducted to compare the environmental impact of professional
composting vs. landfill bioreactors. In these studies, the potential environmental impacts associated
with aerobic composting vs. bioreactor landfills were assessed using the life cycle inventory (LCI) tool.
The results are fairly consistent across the studies performed. These studies concluded that the
emissions to air and water that contribute to human toxicity are greater for the composting option than
for the landfill option and the landfill option yields greater energy savings due to the conversion of the
landfill gas (LFG) to electrical energy.
One such study was conducted at the Michigan State University under the Fulbright Research Grant by
Maria Theresa I. Cabaraban, Milind V. Khire and Evangelyn C. Alocilja and was later published in
November 2007. Their study looked at the potential environmental impacts associated with aerobic invessel composting vs. bioreactor landfilling. The results showed that the estimated energy recovery
from bioreactor landfilling was approximately 9.6 MJ per kg of waste.
The air emissions from in-vessel composting contributed to a global warming potential of 0.86 kg of
CO2, compared to 1.54 kg of CO2 from the bioreactor landfill, meaning the compost produces less global
warming gases. However, emissions to air and water that contribute to human toxicity were greater for
the composting option than for the landfill. In addition, costs associated with in-vessel composting were
about 6 times greater than that for the landfilling alternative. In conclusion, bioreactor landfill was a
favorable option over in-vessel composting in regards to cost, overall energy use, and airborne and
waterborne emissions.
Carbon footprint is often the deciding factor with environmental studies; however there are other
impacts to the environment that are of more immediate consequence. One such factor is chemical
pollutants. Commercial compost facilities produce leachate much like a landfill. This leachate contains
soluble minerals, toxic organic chemicals, pesticides, organic colloids, pathogens and toxic metal (Cd, Cr,
Cu, Hg, Pb, Ni, and Zn). This leachate is produced during the decomposition process in composting.
Commercial compost facilities are required to control the leachate and prevent it from entering
surrounding soil and water tables. Even compost runoff from rainwater is not allowed to be discharged
without a permit.
Under oxygen-limited conditions, the decomposition process also produces methane, nitrogen oxides,
volatile organic compounds, and ammonia. Feedstock high in nitrogen content tends to release
considerable amounts of nitrogen oxides and ammonia if anaerobic conditions prevail in the compost
pile. (Nirmalya Chatterjee, 2013) Ammonia production is inevitable in composting. Ammonia
contributes to acid rain formation, contaminates surrounding areas with excess nitrogen and causes foul
odors. (Food, 1996)
Note: The environmental impact of composting in the U.S. may be partially due to poor
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regulations. The federal EPA [U.S. Environmental Protection Agency] has no regulations
for quality of compost, and no plans for creating any. Under Section 503 of the Clean
Water Act, EPA has created regulations for municipal sewage sludge and EPA takes the
position that those regulations could apply to compost.
Unfortunately, EPA used risk assessment to establish its standards for sewage sludge,
and the resulting standards are very permissive. For example, EPA defines sewage sludge
containing 300 parts per million (ppm) of toxic lead as "high quality" and allows it to be
applied to agricultural land. A buildup of toxic lead in soils would almost certainly occur
after prolonged use of compost containing 300 ppm of lead. In contrast, present Dutch
regulations only allow 65 ppm lead in sludge or compost. Germany only allows 100 ppm
of lead in compost. The Canadian guideline for lead in compost is 83 ppm.
The U.S. EPA's permissive standards will allow compost that is toxic to be defined as
"clean" or "acceptable" or "high quality." Thus U.S. regulations may encourage
production of compost that will poison soils, which will in the long run reduce public
confidence in compost (and in government regulations). To succeed with composting,
state and local governments will need to pay attention to the quality of compost
themselves, and not be seduced by the dangerously permissive regulations of U.S. EPA.
When the full environmental impact of industrial composting is considered, we see that composting can
produce greenhouse gases that are 240 times more damaging than carbon dioxide. Toxic leachate is
produced that contains pesticides, toxic metals and other chemicals. And compost can produce foul
odors.
Overall as was shown by Michigan State University, from an environmental perspective, composting is
not always the ideal disposal method and for some materials, there are better options than composting.
With industrial composting requiring double the amount of trucks covering the same routes, the
infrastructure required to process the materials and the emissions from composting; the environmental
impacts of industrial composting should be considered. This is not to imply that composting is always
detrimental, as there are certain wastes that should be composted. We must look at the facts so
educated decisions can be made regarding composting, and the full impact of composting can be
understood.
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Section 4: Challenges of Composting
Once we consider the economic and environmental impacts of composting, and provided for the
scenario it appears beneficial, we then must look at the specifics of plastic in that compost. Composting
of plastic introduces unique challenges beyond the economic and environmental factors inherent with
composting organics. To compost plastics, we must only use specific types of plastic that will biodegrade
in the compost, we must determine how to effectively sort compostable plastics so they are included in
the compost materials, ensure there is not too much plastic in the compost and finally we must increase
the availability and number of compost sites as well as the market for purchasing finished compost.
First, let’s look at how the plastics will get into the compost. There are a limited number of compost
facilities that accept food waste, and even fewer that accept plastics in the food waste. Plastics are
considered a contaminant regardless of their ability to compost. Some compost facilities will accept
compostable plastics mixed with food waste as a necessary method to obtain the food waste. Simply
put, they do not want plastic. Just try calling your local commercial composting site (if there is one near
you) and asking them if you can bring by a truckload of compostable plastics to put in their windrows!
While composters do not want plastic, there are brands who still would like to compost the plastic. So
let’s consider the logistics. Certain plastic products are often comingled with food waste, (i.e. utensils,
plates and cups) so for these specific items it is fairly simple to just leave them with the food waste. If
the food waste is already going to a compost facility it makes the composting of these plastics
considerably easier.
It is also fairly simple to compost plastics in situations where there is a controlled environment such as a
large facility, stadium or public event. In these places it can be much easier to control the types of
plastics discarded at the location. This can allow a sustainability strategy to include only the use of
plastics that integrate into composting. Just be sure that the compost facility is within close proximity to
the controlled environment, otherwise the transportation could undermine the overall benefit.
Compostable plastics that are comingled with food waste or in a controlled environment account for a
negligible percent of the overall plastic waste; for the rest of plastics composting becomes a much more
complicated scenario.
For most plastics composting is not an option as they will not biodegrade in the compost. For the few
types of plastics that are compostable but not already comingled with food waste, the process of going
from a consumer’s possession to finally being composted can be more complex than most realize.
To enter a compost facility, plastics will need to be sorted from other trash, cleaned of any toxicity
(soaps, chemicals, etc.) and then mixed with food waste. Then a separate truck will need to collect this
waste and transport it to a commercial compost facility (which may be several hundred miles away). If
and when the plastics get to the compost facility, they are often sorted out of the organic waste and
shipped to the landfill. (Johnson T. , 2010) So, it can be difficult to get plastics into the industrial
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compost.
Commercial compost facilities are operations designed to rapidly break down organic materials into
nutrient rich soil amendment for resale value. Materials entering these facilities should easily
decompose, leave maximum humus (soil) and minimal to zero toxicity. Additionally, composting
requires a balance of varying materials to create the proper carbon-nitrogen relationship to prevent
delayed biodegradation, fermentation or depleted soils.
Getting the compostable plastics to the appropriate composting facility can be challenging, but there are
other difficulties that can arise. Compostable plastics are not as durable as traditional plastics; so many
times the compostable plastic is blended with traditional plastic. This is fairly common when looking at
food-service ware because the compostable plastic melts in hot food and drinks. To overcome this, the
manufacturer often blends in some traditional plastic during the manufacturing.
By blending traditional plastic with the compostable plastic, it no longer composts. However, it may be
sold and marketed as compostable plastic. Some of these types of products advertise their ability to
compost by putting certification logos on the product, but do not perform once put in compost. This was
seen several years back with the Sun Chips bag, which received widespread publicity when the bag was
shown not to biodegrade in compost as claimed. (Consumer Reports, 2010)
Another issue that can prevent compostable plastics from breaking down is the conditions of the
compost itself. ASTM D6400 tests plastics at very high compost temperatures, much higher than many
industrial compost facilities normally operate. This causes thermal degradation to plastics that may not
occur in real world composting. When plastics thermally degrade, the resulting material can be
biodegradable when the original plastic was not inherently biodegradable.
Earlier this year, Ithaca College banned all compostable plastics from their compost collection because
the utensils labeled as compostable were not biodegrading in their compost system. Removal of the
residual plastic in the compost cost $21,000 in 2014. (Meckley, 2015) In 2014, compostable foodservice
plastics were banned from commercial organics collection in Portland, Oregon. (Kittlestone, 2014) And
in 2010, the University of Vermont also banned compostable plastics in their organics collection for
composting.
These are not isolated incidences, in 2010 a compostable plastics trial was conducted at Miramar
Greenery compost facility. The test included 105 different products, plates, cups, bowls and cutlery all
marketed as compostable and many certified through BPI. At the conclusion of the test only 37 of the
105 products were completely biodegraded. None of the compostable cutlery showed any signs of
biodegradation. (Hailey, 2010)
In 2011, Intervale Compost Products banned biodegradable and compostable cutlery from compost
collections, because not only were some of the products not biodegrading but also because the US
Department of Agriculture considers plastics (including bioplastics) a synthetic material that cannot be
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used in organic agriculture. Organic agriculture is one of the larger purchasers of organic compost.
Many organic farms use compost as a soil amendment, but compost that has had plastics in it, cannot be
used. This reduces the ability of a compost facility selling finished compost at a profit. (Bormage, 2011)
To effectively include plastics in compost processes, several items must be controlled. Any plastic
entering the compost system must biodegrade at a similar rate as the other organic material, it must not
leave toxic or visually identifiable residue and it must not hinder the biodegradation of the other
organics. Ideally, these plastics would biodegrade in the same manner as organic vegetation and leave
the same nutrient rich soil. If there is more than a fraction of plastic in compost, even plastic that
biodegrades, it can create an imbalance of carbon/nitrogen and inhibit biodegradation of the organics.
As such it is important to control the amount of plastics entering commercial compost.
There are however, certain plastic items that could make the most environmental sense to compost –
even given the challenges involved with composting plastics. Items such as spoons, forks, cups and
plates that are used in an environment where they are very likely to be mixed with food waste and
collected for industrial composting, are all good examples of products that should be considered for
composting.
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Section 5: Sustainability with Composting
Commercial composting can be a valuable part of an overall sustainability program when used for food
and yard waste, it can also be beneficial for specific plastic items. However, compostable plastics and
composting of plastics is not always the best option from both an economic and an environmental
perspective.
First, the environmental impacts to create some compostable plastics can be higher than traditional
plastics; and higher in ways that may be more damaging to the environment. Producing compostable
plastics from crop plants requires an increase in commercial farming. Commercial farming is the primary
contributor to our world’s loss of species diversity, water pollution, and destruction of natural
ecosystems. These factors are damaging the resiliency of the earth and are identified as more critical
than global warming.
The environmental impact of compostable plastic production can be reduced with some of the newly
developed processes and types of materials. This includes, plastics made from materials that would
otherwise have become waste (such as ENSO RENEW), plastics from methane gas (Such as BASF’s
methane-to-propylene facility) and plastics from unique sources like algae. These are a good direction
toward creating renewable and sustainable plastics.
Secondly, compostable plastics are not the same as traditional plastics. Often they do not have the same
strength, may not protect the product as well as traditional plastics and can melt very easily at low
temperatures, this can result in requiring more compostable plastic to do the same job as traditional
plastics, higher environmental impact, increased risk of product failure and a requirement to keep the
plastic in temperature controlled environments.
And, once we produce compostable plastics, they must be disposed of properly. Compostable plastics
cannot be recycled together with traditional plastics because they cause damage to recycling equipment
and contaminate the recycled plastics. Compostable plastics can be recycled, but require separate
processing from other plastics. Most recyclers do not accept or recycle compostable plastics.
The proper disposal of compostable plastics is in an industrial compost facility. With the limited
availability of industrial compost facilities it can be difficult for consumers to properly dispose of
compostable plastics and as a result most compostable plastics will ultimately be thrown away into a
landfill. In a landfill, the compostable plastics may not biodegrade effectively.
Compostable plastics typically do not pose a problem for commercial composting, provided they are in
limited quantity. But, compostable plastics are also not of value to compost because the ASTM D6400
compost standard requires 90% or more of the carbon in the plastic to convert to carbon dioxide, there
is little to no carbon remaining in the soil. This means little to no nutrient value to the compost or
economic value for the compost facility.
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This does not imply that we should not compost plastics, but that there are limited situations wherein
composting of plastics is economically and environmentally best. Instead of widespread consumer use of
compostable plastics, it is more effective, from an end-of-life perspective, to use compostable plastics in
specific applications and environments such as restaurants, stadiums and event venues. In these
environments it is feasible to comingle the compostable plastics with food waste provided there is an
industrial compost facility within close proximity.
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Part 3: What Does Nature Do With Waste?
A review of sustainability would be far from complete without discussing the processes of nature. The
best sustainability platforms are modeled after nature and integrate into natural processes. This is
because sustainability ultimately requires us to work in concert with all of the aspects of nature.
Sustainability ultimately is measured by how well a process or product can either work in sync with
nature or have no impact on nature.
We have explored the ways that human societies manage their waste products through landfilling,
incineration, recycling and composting. But, how is waste handled in nature? There must be a very
effective way to handle waste because every living creature and plant produces waste and yet the earth
continues without any excessive buildup of this waste.
In nature, there is no waste because everything gets utilized in a system that is fully sustainable from
which we should replicate our waste management practices. It is a process performed every day within
nature. In nature, the waste products from one organism become the food for others, providing
nutrients and energy while breaking down organic waste in a process called biodegradation.
Biodegradation is when materials are broken down from complex molecules into more simple ones.
Biodegradation is nature's way of utilizing wastes, or breaking down organic matter into simple
materials that can be used as food for other organism.
"Degradation" means decay, and the "bio-" prefix means that the decay is carried out by a huge
assortment of bacteria, fungi, insects, worms, and other organisms that eat dead material and convert it
into new forms. Some organic materials will biodegrade much faster than others, but all will eventually
biodegrade.
The products of this biodegradation become the building blocks for other life processes. This is the same
process used in composting. The food scraps and yard waste are broken down by microorganisms into
nutrient rich soil, air and water. During composting when organic material is decomposed, it is often
referred to as organic recycling, because we are taking the carbon based materials and turning them
back into a form that is beneficial and useable in nature.
Microorganisms are by far the most effective and efficient re-processors on this planet. They make
virtually all carbon based waste materials re-useable through the process of biodegradation.
Biodegradation is the biological breakdown of organic materials by microorganisms into soil, water, and
air.
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To biodegrade complex and synthetic materials, microorganisms secrete special enzymes that catalyze
the degradation and break the material into more simple components such as organic acids. These
organic acids are then further degraded by other microorganisms in to the basic building blocks of
nature; air, soil and water.
Biodegradation can happen fast or slow and
the speed of biodegradation depends on
interactions between the environment, the
number and type of microorganisms present
and the chemical structure of the
compound(s) being biodegraded. (Board,
1999) Oxygen, moisture, nutrients and
microorganisms are very often the limiting
factors in soils.
While microorganisms can degrade most
natural compounds, they often don’t
produce the appropriate enzymes to degrade
many synthetics (man-made materials such
as chemicals and plastics). Over thousands of
Figure 8: Natural carbon cycle made possible through
years, microorganisms have evolved to
biodegradation caused by microbial produced enzymes
produce the correct type of enzymes that will
match natural materials and allow for biodegradation. As humans create new materials (these are called
synthetic materials), there has not been enough time for microorganisms to evolve and adapt to these
new materials, so they do not produce the correct enzymes.
Producing the correct enzyme to biodegrade a material is critical. This is because enzymes are very
specific, meaning that an enzyme must match the material it is intended to degrade, if it does not then
the enzyme will have no effect. Enzymes are much like a lock and key, the enzyme being the key and the
material to be biodegraded is the lock. Only if the key is a correct match, can it can release the lock.
Over time, microorganisms adapt to new materials and learn to produce the correct enzymes. An
example of this evolution has been seen in polyethylene contaminated soil at the polyethylene
production plant of Carmel Olefins in Israel. Polyethylene is considered non-biodegradable; however
after many years of polyethylene contamination in the soil at that factory, it was found that the
microorganisms evolved to biodegrade polyethylene. (D. Hadad, 2004)
Biodegradation of waste materials constitute one of the most important processes in water, sediment,
soil and other ecosystems. There is significant concern regarding synthetic materials that are not readily
biodegradable and not only remain for a very long time but can accumulate over time to dangerous
levels. (Board, 1999)
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By harnessing these natural forces of biodegradation, it is possible to reduce the environmental
contaminants caused by synthetic materials and chemicals. This is a process called bio-remediation, or
remediating/detoxifying through natural biological processes. This can be accomplished through
enhanced bio-remediation which involves increasing the rate of biodegradation by supplying required
nutrients to an indigenous microbial population (bio-stimulation) or by inoculating the site with
microorganisms capable of degrading the target pollutant (bio-augmentation). Biodegradation is
currently used within waste management for organic waste, sewage, landfills, oil spills and other human
produced contaminants.
Biodegradation is the key within nature to convert waste products into a resource. Through
biodegradation all organic materials are broken down into forms that are useable for other organisms to
complete a full circle of sustainability. Biodegradation is currently used to convert many human wastes
into natural materials such as nutrient rich soil, air and water.
Through composting, natural biodegradation is accelerated to convert organic wastes to soil
amendments. Wastewater treatment also accelerates natural forces of biodegradation to break down
organic matter so that it will not cause pollution problems when the water is released into the
environment. Landfills harness biodegradation to convert organic matter into energy and eliminate
contaminants that could otherwise leach into groundwater and soil. Micro-organisms are used to clean
up oil spills and other types of organic pollution.
Each of these is an example of bio-remediation, which is the use of naturally occurring processes to
decrease human pollutants within the environment. Sustainability managers should learn from and
replicate how waste is handled within nature. In doing so they would either ensure their products are
either recycled after use or fit within natural processes of biodegradation so they will return to a natural
form. This is the most effective way to achieve long-term sustainability of product wastes.
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Part 4: Mimicking Nature with Biodegradable Plastics
Nature processes all waste through biodegradation. The process of biodegradation takes complex
materials and breaks them down to simpler forms which are used by other living organisms. This is a
sustainable process that converts waste materials into resources. As humans, we must learn to replicate
this process of waste management to be sustainable.
Today we as a society create many synthetic materials by taking natural products and rearranging the
molecules in a way to create materials with specific properties. This is beneficial from a use perspective
as the new materials are very useful; however once we have used the material it often remains in the
synthetic form and does not readily integrate back into nature.
Plastics are a perfect example; they are created from natural materials that are readily biodegradable in
nature. After we have rearranged the molecules to create the plastic it is no longer readily
biodegradable and once disposed of will remain for hundreds or thousands of years. This prevents the
molecules within the plastic from integrating back into nature and becoming useable for other living
organisms.
This can be overcome by creating plastics that are readily biodegradable and will biodegrade after use in
the disposal environment. Biodegradable plastics can include new forms of plastic, but also includes
traditional plastics that utilize technologies that increase the rate of plastic biodegradation.
Ultimately, as a responsible society we need to ensure our waste materials will integrate effectively back
into natural processes. This means only create synthetic materials that we know will return to nature in
a useable form.
Chapter 1 provides education on different types of plastics that are often confused; degradable,
biodegradable and compostable plastics. Chapter 2 reviews methods to biodegrade traditional plastics
and also as most plastics are disposed of in landfills this chapter discusses how biodegradable plastics
can integrate into landfill operations to provide a steady source of clean energy.
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Chapter 1: Defining Degradable, Biodegradable and Compostable
There is often confusion when discussing biodegradable plastics because there are many terms that are
confused with the word “biodegradable”. These are terms like, oxo-degradable, oxo-biodegradable,
compostable, home compostable, industrial compostable, degradable, photo-degradable, thermaldegradable, etc. Each of these terms describes a different type of material and a different type of
breakdown. These terms should not be used interchangeably.
It should also be understood that these terms all refer to the way a plastic can break down; it has no
relevance on if the plastic is made from renewable or fossil based sources.
In clarifying the meaning of these words, we will start with the broadest category; degradable plastics.
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Section 1: Degradable Plastics
Degradable plastics are simply plastics that will
lose strength and other physical properties due to
exposure to a specific trigger over a designated
period of time. This is a very general category that
includes all the other terms. The breakdown can
be caused by living organisms, exposure to
oxygen, light, heat, or water.
To know what causes the degradation, there is
often a prefix on the word; bio-degradable
(degradation caused by living organisms), photodegradable (degradation caused by exposure to
light), oxo-degradable (degradation caused by
oxygen exposure), hydro-degradable (degradation
caused by exposure to water).
Figure 9: Degradable plastic is a category that
encompasses many forms of breakdown.
All plastics will degrade over time as they are exposed to light and heat, but when these terms are used
in plastic, it means that the plastic will degrade faster than traditional plastic. Plastics can break down
into many forms. They can break down into small plastics fragments or they can break down into nonplastic residue such as soil, air, or water. Often this depends on the cause of the degradation.
Section 1.1: Photo-degradable Plastics
Photo-degradable plastics are plastics that degrade with exposure to light. Most often this is caused by
the UV spectrum of sunlight. If you have ever tried to pick up a plastic grocery bag that has been on the
side of the road and have it fall apart and crumble in your hands, this is an example to photodegradation.
There are some plastics such as six-ring holders for soda cans that have additives put into the plastic to
accelerate the photo-degradation. This means it will become brittle and fragment into smaller and
smaller pieces as it is exposed to UV light. Photo-degradable plastic requires much less UV exposure
than traditional plastics do to degrade.
Photo-degradation does not imply that the plastic itself is gone; it simply breaks it into very small
fragments.
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Section 1.2: Oxo-degradable Plastics
Oxo-degradable plastics are plastics that break down by exposure to oxygen in the air. Plastics are made
oxo-degradable through the use of additives in the plastic. The additives are most often metals or salts
that create weak links in the plastic molecule. Because the strength of plastics is due to their very long
molecule chains, these weak links when exposed to oxygen begin to break and weaken the plastic.
This degradation is very similar to photo-degradation in that both result in a weakening of the plastic
molecule and fragmentation of the plastic into smaller and smaller pieces.
There are some plastics marketed as oxo-biodegradable plastics which claim to biodegrade after the
fragmentation (oxo-degradation). This may be theoretically possible, but sustainability managers that
use these types of plastics should ensure that the plastic will have sufficient exposure to oxygen so that
it will fragment prior to disposal. However, they must also be careful that the plastic will not have
exposure during storage or use of the plastic. Premature degradation could risk product failure and
products contaminated with plastic fragments.
Oxo-degradable plastics do not degrade in landfills. They are strictly intended for plastics that are
littered and are designed to reduce the visible impact of litter.
Oxo-degradable plastics can prematurely degrade if recycled. Recycling requires melting the plastic and
the heat from melting will trigger the oxo-degradable additive and cause degradation of the plastic.
Oxo-degradable additives should not be used for plastics that will most likely be landfilled or recycled.
Section 1.3: Hydro-degradable Plastics
Hydro-degradable plastics are plastics that degrade in contact with water. These plastics can degrade
quickly or over a longer period of time. For hydro-degradable plastics the catalyst for degradation is
water. Very often these plastics will eventually biodegrade.
Sometimes biodegradable plastics are misclassified as hydro-degradable plastics. However,
biodegradable plastics require living organisms to catalyze the biodegradation whereas hydrodegradable plastics only require water.
Hydro-degradable plastics are not as common as other types of degradable plastics.
Section 1.4: Thermal-degradable Plastics
Thermal degradable polymers are plastics that degrade due to heat. While all plastic will degrade with
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heat, thermal degradable plastics typically have additives that make the plastic degrade more quickly
when exposed to heat.
Some plastics such as PLA, are considered commercially compostable, when they are actually thermally
degradable. They can be classified as commercially compostable plastic because the heat of a
commercial compost facility is very high and the PLA will thermally degrades into chemicals that will
biodegrade. So while PLA is not biodegradable, the products of its thermal degradation are
biodegradable.
Thermally degradable plastics are not recyclable with traditional plastics because recycling requires
melting of the plastic and the heat from melting will degrade the plastic and make it unusable. These
plastics can technically be recycled but it will require separation from traditional plastics and a market
for the recycled resin.
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Section 2: Biodegradable and Compostable Plastics
Bio-degradable plastics are plastics that
degrade through the action of naturally
occurring organisms. They break down
similar to other organic materials, like leaves
and wood.
They will biodegrade at different rates
depending on the environment, but they
must break down into base materials, such as
soil, air and water. Biodegradable plastics do
not leave plastic fragments.
There are several categories of biodegradable
plastics that identify the environment where
the plastics will biodegrade. These include
home compostable, industrial compostable
and
landfill
biodegradable
plastics.
Biodegradable plastics can also degrade in
soil, such as when littered, these are covered
in the Home Compostable section below.
Figure 10: Biodegradable plastics include home compostable,
industrial compostable and landfill biodegradable plastics.
Section 2.1: Home Compostable Plastics
Home compostable plastics are biodegradable plastics that will biodegrade in home or backyard
compost piles. These plastics will biodegrade in oxygen rich environments where other organic material
is breaking down. If leaves and grass will biodegrade in an environment, then home compostable
plastics should biodegrade as well.
Plastics that will biodegrade in home compost will also degrade if buried in soil. This would apply to
plastics that may be littered in the open environment.
Home compostable plastics should biodegrade in a similar time frame as other organic material. They
also require the same conditions as most organic material for biodegradation to occur. A good rule of
thumb is, if other organic material is breaking down around it, home compostable plastics will most
likely biodegrade as well.
Home compostable plastics should not leave any toxic residue in the soil after biodegradation.
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Section 2.2: Industrial Compostable Plastics
Industrial compostable plastics, also known as commercially compostable plastics, are plastics that
biodegrade in the controlled conditions of a commercial/industrial compost facility. This is not the same
as a home compost and plastics that biodegrade in an industrial compost will not necessarily biodegrade
in home compost. Additionally, industrial compostable products may not biodegrade in a landfill.
Industrial compostable plastics often require very high heat to initiate breakdown (see thermaldegradable plastics) and the breakdown is followed by biodegradation. Many compostable plastics are
not biodegradable in any environment except industrial compost facilities.
ASTM D6400 is a specification for industrial compostable plastics. It requires that at minimum 90% of
the plastic converts to carbon dioxide within 180 days. This means that the plastic must nearly entirely
convert to air, which leaves no nutrients in the soil. ASTM D6400 also requires that toxicity tests be
performed to ensure that there is no toxic residue in the compost. The primary focus of ASTM D6400 is
to make sure the plastic does not interfere with the commercial aspects of industrial compost
operations.
Industrial composting is a man-made managed environment; it is not an environment that occurs in
nature. In industrial compost, conditions are optimized to maximize the rate of biodegradation so that
the compost can be sold as quickly as possible. This means, high heat, controlled moisture, optimal
oxygen flow, balanced carbon/nitrogen ratios and a multitude of other conditions that are monitored
and controlled.
Because industrial composting is not a natural environment, plastics that biodegrade in this
environment may not biodegrade in other environments such as, soil, backyard compost, landfills,
oceans and roadsides. Therefore, the biodegradation of industrial compostable plastics are only
beneficial when the plastic will be disposed of in an industrial compost facility.
Section 2.3: Landfill Biodegradable Plastics
Landfill biodegradable plastics are plastics that will biodegrade in a landfill environment. Landfills are
considered one of the more difficult places to achieve biodegradation; there is little to no oxygen, no
light, reduced moisture and the materials are under pressure. Most often a material that will biodegrade
in a landfill, will biodegrade in soil, compost and other natural environments (though not always in the
time frame needed for industrial business purposes).
Landfill biodegradable plastics should biodegrade within 2-50 years; this is much longer than the time
restriction for industrial compostable plastics. This is because a landfill does not need to have material
ready to sell in a short period of time like an industrial compost facility would. The primary factor for
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landfill biodegradable plastics is that they biodegrade in the landfill using the microorganisms that are
naturally occurring in the landfill and they biodegrade without need for exposure to light, oxygen or
heat.
There are several tests used to verify the biodegradability of plastics in the landfill, ASTM D5511, ASTM
D5526 and Biochemical Methane Potential testing. Each of these tests validates biodegradability in
landfills by measuring the conversion of the plastic to carbon dioxide and methane. The ASTM D5511
and Biochemical Methane Potential tests show accelerated results in ideal conditions and the ASTM
D5526 is meant to more closely replicate the conditions in a landfill to provide more realistic time
frames for biodegradation.
Landfill biodegradable plastics are an important part of an overall sustainability strategy because 90% of
all plastics end up in landfills and landfill biodegradable plastics provide a means to ensure the positive
end-of-life for that plastic.
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Chapter 2: Biodegrading traditional plastics
Plastics are a key development for modern society, however, they also have the negative impact of not
biodegrading – they last for hundreds to thousands of years. In learning to replicate natural processes, it
is apparent that plastics should be biodegradable. It is also clear that they should be biodegradable in
the landfill because that is where most plastics will be deposited.
To create biodegradable plastics, there are two primary areas of focus: create new plastics with inherent
biodegradability or utilize microorganisms with the ability to biodegrade plastics so traditional plastics
will be biodegradable.
There are many new plastics that are biodegradable. Some of these plastics may hold great promise for
the future of plastics. There are others that lack the properties we require of plastics; these ones are
weaker, more expensive and not as good as traditional plastics. Many of these plastics are considered
“compostable plastics”. The environmental impact to produce these plastics is reviewed in the section
“Creating Compostable Plastics”.
Most of the newer inherently biodegradable plastics are still in the development process. There are
improvements being developed that will make inherently biodegradable plastics more similar in
performance and durability to traditional plastics without affecting the biodegradability. And, increasing
production to commercial scale so pricing can be reduced and make the materials more economically
feasible. Ultimately, some of these plastics will find success in the market but there is still some work to
be done before they can replace traditional plastics on a broad scale.
The most promising area for biodegradable plastics is in making traditional plastics biodegradable
utilizing naturally occurring microorganisms in the traditional waste disposal environment. So how can a
synthetic fossil fuel based material ever be biodegradable?
There is a common misconception that it is impossible for traditional plastics to biodegrade. This stems
from a lack of knowledge regarding polymer chemistry and microbiology; plastics are often considered
synthetic materials, yet a look at the atomic composition reveals that the polymer chain is comprised of
primarily carbon and hydrogen – the same primary materials in natural organic materials. The difference
between natural and synthetic materials is simply the configuration of the atoms. With the correct
enzymes, any carbon based material has the opportunity to biodegrade in the same manner as plant
matter.
Traditional plastics are made from fossil fuels and most often petroleum. Many people believe that
petroleum is a horrible chemical that we extract from the earth. But, petroleum is simply fossilized
algae. What this means is that petroleum and fossil fuels are plants, just like the plants that grow today,
that have been fossilized. The carbon and hydrogen that make up fossil fuel is the same as the carbon
and hydrogen that make up plant matter.
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While the carbon and hydrogen atoms are the same, when we make plastics we are rearranging the
atoms. We arrange the atoms into molecules like ethylene and propylene. Ethylene and propylene are
still biodegradable. However, in the next step we take these molecules and polymerize them.
Polymerization is taking smaller molecules, like ethylene and propylene, and connecting them together
into very long chains. This creates polyethylene and polypropylene (-poly means many, so many
ethylenes and many propylenes). Once in these very long chains, they are no longer considered
inherently biodegradable because the molecule is too big for microorganisms to work with. To
biodegrade it, first the microbes will need to produce the right enzymes to release the bonds holding
the chain together. But, these are fairly new materials and the microorganisms are not producing the
right enzymes to allow biodegradation.
Figure 11: Process of polymer biodegradation
Over the years, there have been concerted
efforts to understand microbial plastic
biodegradation. It is known that bacteria as well
as fungi are capable of biodegrading plastic, but
that plastic biodegradation is a slow process.
Historically it was believed that the
biodegradation of the plastic backbone was
initiated by oxidative cleavage and hydrolysis
(Sudhakar, 2007) of the carbon bonds (G. N.
Onyeagoro, 2012). More recently, isolated
strains of bacteria have been identified that are
able to secrete extracellular enzymes capable of
biodegrading plastic.
Once the microorganisms secrete the correct extra-cellular enzymes, those enzymes begin to shorten
the polymer chain. The resulting low molecular weight materials are then further utilized by the
microorganism as carbon and energy sources. The ultimate products of this biodegradation are CO2,
CH4 (in anaerobic conditions), H2O and biomass.
For the benefit of managing our plastic waste, we must have biodegradation occur within a time period
that is beneficial for the specific environment. For example, if plastics are put into a commercial
compost facility, the plastic should biodegrade as rapidly as possible and in no more than 180 days. This
is because commercial composting is a business activity and they need to sell the compost within 180
days. If there are plastics remaining in the compost, the compost facility will need to filter out the
plastics and further process the compost. This increases the cost and time required before the compost
can be sold. So, for composting the key driving factor in the rate of biodegradation is the resell value of
the compost.
For plastics that are in a landfill, the biodegradation must be slower than compost. If the plastic
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biodegrades similar to compost, in 180 days, then the gas that is produced during biodegradation will be
released into the atmosphere. Ideally, plastics in the landfill should biodegrade within 2-50 years (the
time during which a landfill is actively managed and methane is captured). Ideally, the plastic needs to
biodegrade in the same manner and time frame as slower degrading organic materials like yard waste
would in the landfill environment.
We know that most all plastics are going into a landfill, and that these plastics need to biodegrade within
2-50 years. But, traditional plastics take hundreds of years to biodegrade. To solve this, a technology has
been developed that increases the rate of plastic biodegradation in the landfill.
As we discuss this technology, keep in mind that plastics are made of carbon and hydrogen from
fossilized plants and the only reason they don’t easily biodegrade is because the polymer chain is so long
and the microorganisms aren’t familiar with producing the right enzymes needed to biodegrade the
plastic. So rather than change the plastic, what if we can teach the microorganisms how to produce the
right enzymes?
This advancement is unique in that it does exactly that! Older concepts tried to alter the plastic molecule
but this caused weak plastics that did not work well and often fell apart before they were ever used. The
modern method is to work directly with the naturally occurring microorganisms that are already in the
landfill and encourage the production of plastic biodegrading enzymes.
ENSO RESTORE™ is one such method which employs a unique blend of materials designed to not only
attract specific naturally occurring microorganisms, but to induce rapid microbial acclimatization to
synthetic plastics and resulting biodegradation. In simple terms, this means that by exposing
microorganisms to specific types of
materials we can alter the types of
enzymes they produce. And we can
induce the right types of enzymes that
will biodegrade the plastic.
The benefit of this method of
enhancing biodegradation is in the
retention of the plastic properties. We
can have the same strength, durability
and low cost that we do with
traditional plastics. And, the plastic
will remain intact throughout its
service life and will biodegrade only
upon disposal in the landfill or an Figure 12: Microbes utilize enzymes to release atomic bonds and rearrange
the atomic structure of materials
environment with active microbial
diversity.
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Once the plastic is deposited in the landfill, the action begins. Naturally occurring microorganisms are
attracted to the plastic and the technology induces the production of plastic biodegrading enzymes.
These enzymes effectively depolymerize the plastic and allow the conversion of the plastic into natural
components - the same end products resulting from the biodegradation of plant matter.
The biodegradation is faster because when microorganisms come in contact with plastic using
technologies, such as ENSO RESTORE™, they have a readily available energy source and that energy
source causes them to begin producing specific types of enzymes. The enzymes they produce are exactly
the ones needed to biodegrade plastic.
This is a method of biodegradation designed to integrate into landfills. The process works very
effectively in the conditions of a modern landfill, and allows all the benefits of traditional plastics. By
utilizing natural biodegradation within the landfill and doing it in the optimal time, we not only return
plastics to a natural form but we also create clean energy.
Let’s discuss what that energy profile would look like.
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Section 1: Creating Energy through Biodegradation of Landfilled Plastic
Understanding that billions of pounds of plastics are disposed of within landfills, and also that the
current trend worldwide is the capture and use of landfill gas (methane) to produce power, it is a logical
conclusion that converting this landfilled plastic to methane is an optimal energy strategy. We can either
leave traditional plastics as they are, and they will slowly biodegrade over hundreds of years, releasing
methane directly into the atmosphere, or we can use technologies like ENSO RESTORE™ to biodegrade
the plastic faster so the methane can be a resource for communities. Either way, the methane will be
produced – why not utilize it?
The value of landfill gas is well understood and currently utilized statewide, federally and throughout
the world. Landfill gas is part of many renewable energy strategies and it also reduces the overall
greenhouse gas emissions of a community. Including plastics in this process is a natural progression that
maximizes the value of our energy from landfills and also of the plastics themselves.
How much energy would we produce by using biodegradable plastics in the landfill?
In the US, we landfill 63.6 billion pounds of
plastic each year. If this plastic3 was
biodegradable in the landfill and was
placed in landfills converting methane to
energy, the 63.6 billion pounds landfilled
each year would produce 66.2 trillion Btu. 4
This is a significant amount of energy, but
to many people the term BTU is foreign
and hard to understand what impact that
really is. If we are to look at the energy
value from using biodegradable plastics in
the landfill in terms more understandable,
we have the following:
Figure 13: Energy/fuel value of biodegradable plastics in landfill gas
energy projects (US only)
3
To calculate the energy value one must know the actual carbon content and methane conversion ratio of each
discarded material, for purposes of this report we will use an average of 86% carbon for synthetic plastics.
4
To calculate how much energy can be created from the biodegradation of landfilled plastic waste we take the
total weight of plastic waste (69,850,000,000lbs), remove the 9% recovered for recycling and we are left with
63,563,500,000lbs landfilled annually. We then multiply it by % carbon (approximately 90%), multiply by 1.33
(molecular weight of CH4 16 / molecular weight of carbon 12 – this converts the carbon to methane), then multiply
by 22.4 (L/g – ideal gas law). This will provide the volume of methane potential, which we then convert to cubic
meters (1,704,315,412m3 or 60,187,330,726ft3). Assuming that the gas production is approximately 70% methane
and 30% carbon dioxide, we then multiply by .7 to achieve the actual methane potential value. The energy value is
calculated using an average of 7 barrels per TOE and the 1TOE energy equivalent of 39.68 million Btu as defined by
the US EIA.
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Biodegradable plastics in landfills converting methane to energy would save an equivalent to 11,703,092
barrels of oil, be enough energy to fuel the annual usage of 868,826 cars5 or provide power to 1,609,980
homes each year6
This means that by biodegrading our plastics in energy generating landfills, we could power 20% of all
the homes in New York, all of the homes in Oregon or power all of the homes in Nevada, North Dakota
and South Dakota!
These energy values are only the direct conversion of the methane resulting from landfill
biodegradation. Calculating the overall energy/carbon savings considering the offsetting of coal
produced energy, the reduced transportation cost by remaining integrated with municipal waste, and
the avoided energy of handling/reprocessing in alternative methods, the actual realized benefit would
be far greater.
With the current pressure on energy utilities to convert from coal to more “green” energy sources,
utilizing biodegradable plastics as a way to increase the energy output of landfills should be a very
serious consideration.
5
1 barrel of oil = 42 gallons: driving 1400 km (840 miles) in average car, the average vehicle miles traveled in 2011
was 11,318 miles per year, equivalent is 13.47 barrels/vehicle/year - US EPA
6
Average home electricity use in US (2013) - 12,069Kwh
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Part 5: Testing and Validation for Degradable, Biodegradable and
Compostable Plastics
Sustainability managers need to make decisions based on factual data, an important part of that data is
validating the performance of materials. The validation when referring to degradation and
biodegradation will be in the form of laboratory testing. To evaluate data and validation, one must
know what test methods are available and which ones will apply to a specific product and disposal
environment.
There are several methods employed to study the degradation and biodegradation of plastics. If one is
looking to confirm degradability, than tests are used that measure the change in physical characteristics
such as; physical weight loss, disintegration, brittleness, fragmentation or molecular weight.
To test biodegradation, the most effective and accurate measurement is that of gas production. This is
because the gas production is the result of microbes taking the carbon atoms in the plastic and
converting them into carbon dioxide and/or methane. Gas production is not seen when plastic simply
fragments, so measuring gas production confirms the microorganisms are breaking the plastic apart, not
exposure to other elements such as water, heat, light or oxygen.
The appropriate test for a plastic is determined by where that plastic is most likely to be disposed. To
test a plastic for industrial compostability when the plastic will be disposed of in a landfill does
absolutely no good, it will not validate the products customary disposal and end-of-life environment.
Therefore, for sustainability managers, the first objective is to determine the most likely place your
plastic will be sent, and then require testing based on that environment.
It is also important to understand the test reports and what to look for. Some organizations promote
that 90-100% of the carbon in the plastic must convert to gas during testing to prove biodegradability.
This is a misconception based on the industrial compostable plastic requirements of the ASTM D6400.
Remember the key to D6400 is to validate plastics will not impact the commercial value of compost, so
the key is to have the plastic “disappear” or convert as completely as possible to air/gases.
When considering biodegradation in
general, converting all the carbon is
not as important as it is to validate
that the microorganisms in the
disposal environment have the
ability to biodegrade the plastic. This
is because the plastic is made up of
the same molecules throughout,
meaning that a polyethylene
molecule in plastic is the same as the
Figure 14: Magnification of a polyethylene bag shows how it is made of
millions of identical polyethylene molecules that all have the same
properties and the same biodegradability. If one molecule of polyethylene
biodegrades, so will the others.
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rest of the polyethylene molecules. If the microorganisms can biodegrade one of the polyethylene
molecules, then they will also biodegrade the rest.
Note: When looking at the biodegradation percentage of plastic, while there is no need
to achieve complete biodegradation or any specific percentage of biodegradation during
the test, it is important to exceed the percentage of any additives put into the plastic.
This will ensure that the plastic molecule is biodegrading and not just the additives.
Many falsely represent biodegradability testing by stating that the only test for biodegradability is ASTM
D6400. However, as we have established the ASTM D6400 relates only to plastics entering into an
industrial compost facility; it does not confirm biodegradability in any other environment. Thus, ASTM
D6400 should only be used to validate industrial compostability of plastics.
Testing for degradability or biodegradability should be relative to the final disposal environment to
ensure performance during real world scenarios. For plastics entering an industrial compost facility,
ASTM D6400 is the most appropriate testing. Plastics that will most likely be placed into a landfill should
be tested using landfill based conditions as are used in ASTM D5526, ASTM D5511 and Biochemical
Methane Potential tests.
The testing should also take into account what you are testing for; are you looking to see degradability
/fragmentation or biodegradability? If biodegradability is your goal, then tests that measure conversion
of the plastic to gas such as, ASTM D6400, ASTM D5526, ASTM D5511 and Biochemical Methane
Potential, should be used. If the desire is to break the plastic into small pieces, then degradable tests
such as ASTM D5272, D5208 and D7473 should be used.
Part 5 is organized into 3 chapters, each focusing on testing of a specific category. Chapter 1 will cover
what degradable tests measure and ASTM tests specifically related to degradable plastics. In chapter 2
we look at tests that measure the biodegradability of plastic. Chapter 2 also contains a special section
relating to the importance of microbial diversity in testing that can assist laboratories and sustainability
managers in performing valid biodegradation tests. Chapter 3 will address testing for industrial
composting of plastics.
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Chapter 1: Degradable Testing
Remember, degradable plastics are those that break into smaller and smaller pieces when exposed to
specific triggers such as UV light, heat and oxygen. Testing for degradation of plastic is to determine how
a specific condition will deteriorate the strength of the plastic. These tests typically expose the plastic to
a condition that would stimulate degradation and then measure the result by weight loss, brittleness,
fragmentation or reduced molecular weight (meaning that the plastic molecules have broken into
smaller pieces).
Some tests that measure the degradability of plastic include; ASTM D5272, ASTM D5208, ASTM D7473
and ASTM D6954.
ASTM D5272 - Standard Practice for Outdoor Exposure of Photo-degradable Plastics
This is a test for degradation caused by exposure to UV light. In the laboratory the plastic is put under
lamps that simulate prolonged exposure to the sun’s UV light. Degradation is measured by reduction in
molecular weight of the plastic and brittleness of the plastic. This tests if a plastic will degrade/fragment
if left in the open environment where it is exposed to natural sunlight for extended period of time.
This is an appropriate test for photo-degradable plastics that are expected to be littered and the desire
is to have the plastic become brittle and then break into smaller and smaller pieces as it sits exposed to
the sunlight. This test does not measure biodegradability or verify if the plastic will have toxic effects on
the surrounding soil and biota.
ASTM D5208- Standard Practice for Fluorescent Ultraviolet (UV) Exposure of Photodegradable Plastics
This test is designed to measure the degradation of plastic when littered in the open environment or
roadside. This test is performed in a laboratory by exposing the plastic to heat, UV light and moisture.
After exposure the plastic is measured to see if it has lost strength and become brittle or broken into
small pieces.
This is an appropriate test to perform if you have an oxo-degradable, thermal degradable or photodegradable plastic that will be littered and the desire is to have the plastic become brittle and then
break into smaller and smaller pieces as it sits exposed to the sunlight, oxygen and moisture. This test
does not measure biodegradability or verify if the plastic will have toxic effects on the surrounding soil
and biota.
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ASTM D7473 - Standard Test Method for Weight Attrition of Plastic Materials in the Marine
Environment by Open System Aquarium Incubations.
This test is used to measure how much weight is lost when a plastic is exposed to sea water. This can
include weight loss from small fragments of plastic leaving the plastic product, the plastic dissolving in
the water, or biodegradation of the plastic – however it does not determine which is actually happening.
This test only determines if the plastic is losing weight.
This is an appropriate test for hydro-degradable plastics that will be littered in the ocean and you want
to know if it will remain in one large piece, or if it will get smaller. This test does not determine how the
plastic is losing weight (fragmenting, biodegrading, dissolving), it only identifies if the plastic will lose
weight.
ASTM D6954 - The ASTM D6954 is the Standard Guide for Exposing and Testing Plastics that
Degrade in the Environment by a combination of Oxidation and Biodegradation.
This is a hybrid test that first exposes the plastic to heat, light and oxygen to fragment the plastic into a
plastic powder, and then checks the resulting powder for biodegradability in soil, landfill or industrial
compost.
This testing is appropriate for plastics that will be littered or exposed to sunlight, heat and oxygen for
extended periods of time before biodegradation is expected. This can be used for plastics that are used
as soil cover or agricultural films that will be exposed to the elements and is not expected to be removed
for disposal.
Note: If the plastic will ultimately be disposed of in a landfill or industrial compost, it may
be impossible to collect or contain the plastic once it is in a powder form so it is
important to ensure there is a collection method that can expose the plastic to sunlight,
heat and oxygen for a sufficient time to fragment it into a powder, and then contain it
for transportation to the industrial compost or landfill.
This test does not verify if the plastic will biodegrade if it is landfilled or composted prior to the plastic
degrading to a powder. If the plastic will not be exposed to sufficient light, heat and oxygen prior to
disposal – this is not an appropriate test.
This is an appropriate test for oxo-degradable plastics that are marketed as oxo-biodegradable that are
expected to be littered in the environment.
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Chapter 2: Biodegradable Testing
Biodegradable tests are designed to verify the ability of microorganisms to break down plastic into air,
soil and water. These tests measure biodegradation by how much of the carbon in the plastic is
converted to carbon dioxide or methane.
Biodegradation testing is more robust
and more sensitive than degradation
testing. This is because there are more
variables involved and the tests include
living organisms (microorganisms). This
means that not only the conditions of
the test be monitored but also
variables that could affect the behavior
or types of microorganisms in the test
must be addressed.
Figure 15: Biodegradation tests attempt to replicate specific environments
When testing with microorganisms it is
to ensure biodegradation will occur in real world applications.
important to understand microbiology.
Sustainability managers don’t need to know the details of microbiology; that is the laboratory’s
responsibility. However it will be beneficial to understand that microorganisms are everywhere. There
are more microorganisms in a spoonful of dirt than there are people on this earth. There are also
millions of different types of microorganisms; so many that we have yet to identify even a fraction of the
microorganisms on this planet.
There are different types of microorganisms in home compost, when compared to industrial compost
and different ones still in the landfill. This is because in each of these environments the temperature,
moisture and oxygen levels are different. Some microorganisms that thrive in home compost will die if
exposed to the high heat of industrial compost conditions. Many of the microorganisms that exist in
home compost and industrial compost cannot survive in the landfill where there is limited oxygen.
The microorganisms in each of these environments will also adjust based on the food source available.
For instance, if there is a large amount of cellulose in the environment than microorganisms that easily
digest cellulose will populate and the microorganisms that do not digest cellulose will die off. If the food
source changes the types of microorganisms will adjust based on the food source so the ones that can
digest the new food source will be the most prevalent.
This makes the testing of biodegradation very sensitive to what type of food source the soil has been
exposed to as well as what environmental conditions it was prepared in. Biodegradation tests are
designed to replicate the appropriate environmental conditions and ensure the soil has been exposed to
food sources that are expected to be available in the disposal environment replicated.
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Note: Some laboratories that do not understand the microbiology details erroneously
use incorrect inoculum or inoculum that has not been exposed to the diverse food
sources that will be available in the actual disposal environment. This can cause invalid
results. See section titled “Importance of Microbial Diversity in Testing” for further
understanding on this topic.
The two primary categories for biodegradable plastic tests are aerobic and anaerobic, meaning with
oxygen and without oxygen. The biodegradation pathway is different in aerobic vs. anaerobic
environments. In general, a material that will biodegrade anaerobically, will also biodegrade aerobically;
but the reverse is not true. Biodegradation anaerobically is typically much more difficult, so materials
that will biodegrade aerobically do not necessarily biodegrade anaerobically.
Aerobic testing includes ASTM D5988 and ASTM D6400. The ASTM D6400 uses the high heat of
industrial composting which biodegrades materials as fast as possible, whereas the ASTM D5988 is
ambient temperatures as would be found in natural soil environments which can be slower more
natural biodegradation. Therefore the biodegradation results with ASTM D6400 vs. ASTM D5988 are
usually much faster.
Anaerobic biodegradation testing includes ASTM D5511, ASTM D5526 and Bio-chemical Methane
Potential (BMP) testing. The ASTM D5511 and BMP tests have optimal conditions to biodegrade
materials as fast as possible in an anaerobic environment, therefore the biodegradation results with
ASTM D5511 and BMP tests are typically much faster than the ASTM D5526.
Section 1: Importance of Microbial Diversity in Testing
It is the microbial processes that govern the biodegradation of materials and the resulting gas
generation. (Associates) That means that the biodegradation of plastic is controlled by the
microorganisms around it. When testing plastics for biodegradation, the activity and types of
microorganisms will often determine the results of the test. For this reason it is important to run tests
that not only replicate the disposal environment but that also have maximum microbial diversity. If the
correct types or quantities of microorganisms are not in the test inoculum than the test may fail even
though the plastic will in fact biodegrade in the actual disposal environment.
For compost testing, both home and industrial, it is fairly simple to create inoculum with similar
microbial population as is found in these environments because they are fairly controlled; meaning that
the food source is typically limited to organic materials (plant matter) and the conditions are controlled
(temperature, moisture, oxygen availability). Because the food source is limited to plant matter in the
actual disposal environments, a laboratory can easily create compost from plant waste and have
microbial populations very similar to the real world environments.
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Testing for landfills requires a more thorough understanding of microbiology for the laboratory. Because
all different types of waste is disposed of within landfills (organics, chemicals, metals, plastics, and
minerals), the types of microorganisms are much more divers than in composting. This is because the
food source is much more diverse. The microorganisms also must be those that can survive in limited
oxygen environments.
Within landfills, many types of microorganisms have been identified that contribute to the
biodegradation of materials and resulting methane production. It is also well recognized that only a
fraction of these microorganisms have been identified and even fewer are cultivable in the laboratory.
This means that most of the microorganisms that thrive in the landfill, do not survive in the laboratory.
Thus many laboratories struggle with biodegradation testing related to landfill conditions due to a lack
of expertise in microbiology.
Though not presented in this paper, it is recognized that laboratories who source inoculum from inhouse processes very likely have limited diversity in microorganisms leading to inaccurate test results.
This is because of the inability to cultivate a vast majority of microorganisms that dwell in a landfill
within a laboratory. This is also due to the problematic nature of attempting to simulate the
organic/inorganic matrix within a landfill, the different types of materials in a landfill are so varied that it
is difficult to replicate in a laboratory.
Laboratories that do not understand landfill microbiology often mistaken that microbial flora within
native soil, compost or anaerobic digesters are adequate for landfill biodegradation testing. Compost
and soil contain significant colony forming units and have a wide variety of bacteria and fungi that are
optimized within aerobic environments, but not in anaerobic ones. Anaerobic digesters most commonly
use plant and vegetation waste so although they do encourage the growth of anaerobic
microorganisms, the system lacks the varied food sources that would be available to microorganisms in
a landfill and so the resulting microbial flora is limited to those that digest plant matter. To perform
landfill tests using this type of inoculum lacks scientific credibility and renders the results of testing
invalid.
In these scenarios it is far more common to observe false negatives due to inadequate microbial
diversity as opposed to false positives. To avoid false negatives and provide more valid test results,
laboratories can utilize landfill leachate as a basis for inoculum used for landfill biodegradation tests. The
landfill leachate will provide a better, though not complete, distribution of the types and quantities of
microorganisms that occur in actual landfills. Laboratories undertaking biodegradation testing of landfills
will find repeatable results by obtaining microbial flora from landfill leachate. It is not recommended
that laboratories utilize inoculum produced in-house for landfill testing.
Another limitation to be considered is the use of commercially produced cellulose as a test sample to
measure microbial activity. It has been found that commercially produced cellulose can have up to 10X
greater activity than the level indicated by the vendor. (Barlaz, Microbiology of Solid Waste, 1996)
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Cellulose is used in biodegradation testing to validate that there are viable microorganisms in the
inoculum. If the cellulose biodegrades faster than advertised or expected, the laboratory could falsely
identify inoculum as viable when in fact the microorganisms are lacking. This can cause false negatives,
but is not as common as false negatives due to a lack of microbial diversity in the inoculum.
In short, laboratories performing testing should take great care to ensure that the microorganisms in
their test soil are as diverse as possible and reflect the microbial flora that exists in the environment to
be tested. Different microorganisms thrive on different types of materials, so if a laboratory creates
inoculum using manure or vegetable waste only then the primary microorganisms will be those that
thrive on manure and vegetable waste. To try and test for biodegradation of plastic in this environment
would very likely provide false negative results simply because there is limited diversity in their
inoculum.
For testing of compostable plastics, both home and industrial compost, the inoculum should be created
using primarily food and yard waste. This can be done by using compost from an industrial compost
facility or by creating the inoculum in-house with the use of food and yard materials.
If a laboratory is testing for a landfill environment, there are many diverse materials including plastics,
metals, rubber, food, chemicals, paper, wood, etc., in the landfill and this means that the
microorganisms that thrive there will be diverse as well. As such, a laboratory should prepare inoculum
either using landfill leachate or in other ways ensure that the inoculum is exposed to this wide variety of
materials for a time sufficient to ensure the growth and colonization of a diverse array of
microorganisms that would normally be found in a landfill. This will provide the most reliable
biodegradation test results for confirmation of real world application.
ASTM D5988 - Standard Test Method for Determining Aerobic Biodegradation of Plastic
Materials in Soil
ASTM D5988 is a test that measures the biodegradability of plastic that is littered or buried in soil. The
test measures the complete biodegradation of the plastic molecule into carbon dioxide, the endpoint of
aerobic biodegradation.
This test is appropriate for plastics that will be buried or littered in the soil and the ultimate
biodegradation of the plastic is important. Because the test measures biodegradation by conversion of
the carbon in the plastic to carbon dioxide, there is no concern for plastic fragments remaining in the
soil. An example of an appropriate application would be agricultural soil covers where the desire is to
leave the plastic in the soil and ensure it completely biodegrades.
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ASTM D5526 - Standard Test Method for Determining Anaerobic Biodegradation of Plastic
Materials under Accelerated Landfill Conditions
ASTM D5526 is the test that measures biodegradability of plastics that are disposed of in the landfill. It
measures the conversion of carbon from the plastic into carbon dioxide and methane, the end points of
anaerobic microbial biodegradation. This is the most appropriate test for plastics that will ultimately be
landfilled.
In landfills, moisture is a critical factor to how fast materials will biodegrade, however in landfills
moisture will vary depending on the region and landfill design. For this purpose, the ASTM D5526 test is
performed at three different moisture levels representing a very dry landfill (such as would be seen in a
desert region), a very wet landfill (as would be seen in tropical region) and a moderately moist landfill
(an average of moisture rates across various landfills).
The ASTM D5526 test is performed under pressure, with lower temperatures and without oxygen as
would be seen in a landfill. This test is meant to replicate the environment of a landfill as closely as
possible and give more realistic biodegradation rates than other landfill tests.
The ASTM D5526 test is the most appropriate test for plastics that will end up in a landfill. With 90
percent of plastics being disposed of in a landfill, the ASTM D5526 is the most appropriate test for the
majority of plastic products.
ASTM D5511 - Standard Test Method for Determining Anaerobic Biodegradation of Plastic
Materials under High-Solids Anaerobic-Digestion Conditions
The ASTM D5511 test measures the biodegradation of plastic in landfills that have high moisture and
optimize biodegradation as well as biodegradation in anaerobic digesters. The ASTM D5511 measures
biodegradation by the conversion of carbon in the plastic to carbon dioxide and methane.
The ASTM D551 test uses higher moisture and higher heat than the ASTM D5526, but the test is still
anaerobic. Whereas the ASTM D5526 test uses multiple moisture rates to demonstrate how the
moisture will change the rate of biodegradation in a landfill, the ASTM D5511 is meant to simply
determine biodegradation in an optimal anaerobic environment.
Biodegradation rates in the ASTM D5511 are typically faster than the rates seen in the ASTM D5526 for
the same material; this is because the ASTM D5511 is more optimal conditions for biodegradation. So
while the determination of landfill biodegradability can be made using the ASTM D5511, the actual rate
of biodegradation in the landfill will most likely be much slower than the test results indicate.
The ASTM D5511 test is appropriate for plastics that will be landfilled or disposed of in an anaerobic
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digester.
Biochemical Methane Potential
Biochemical methane potential (BMP) testing is an anaerobic test used by researchers and academia
worldwide to study the biodegradation of materials in landfills. The BMP test is similar to the ASTM
D5511 in that it uses optimal conditions to try and biodegrade materials as quickly as possible. The BMP
test is meant to determine if materials will biodegrade in the landfill, but not determine how fast.
The BMP test is not a standardized test method, so there is more flexibility in the test protocol to adjust
parameters as desired to evaluate different scenarios. The BMP is the test of choice for many
researchers and academia due to the flexibility of the test parameters.
The BMP test typically utilizes higher temperature and moisture as is done in the ASTM D5511 and the
test is anaerobic like the ASTM D5511. Often the test is run nearly identical to the ASTM D5511 with the
exception of the sample size; the plastic sample and amount of inoculum on the test is reduced to
minimize the space required in the laboratory. Another adjustment can be to recirculate the leachate
during the test period to replicate a bioreactor landfill.
The BMP test is most often used as a litmus test to determine the biodegradability of a material.
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Chapter 3: Compostable Testing
Compostability of plastics typically refers to industrial compostability. The conditions in a compost
facility are unique because the environment is highly controlled to accelerate biodegradation as quickly
as possible. One of the factors that accelerated the biodegradation is very high heat; this heat often
thermally degrades plastic which can make it more readily biodegradable.
Industrial compostability testing validates biodegradability in industrial compost facilities only; it does
not verify biodegradability in landfills, home compost or ambient soil.
ASTM D6400 - Standard Specification for Compostable Plastics
ASTM D6400 is designed to ensure that plastics intended for an industrial compost facility will
biodegrade very rapidly and leave no trace or toxicity in the compost soil. This test uses very high heat
and controlled moisture/oxygen levels to replicate a high temperature industrial compost facility.
ASTM D6400 includes testing for fragmentation, biodegradability and verifying that there is no residual
toxicity. This is a specification rather than a test because it includes specific performance time frames
and parameters to pass the specification. The ASTM D6400 was created to ensure plastics would not
compromise the commercial aspects of industrial composting, for this purpose it is important to have
specified time frames for biodegradation.
Some plastics that are not inherently biodegradable can pass the ASTM D6400 if after an initial
degradation the plastic biodegrades. This is seen with PLA that is not biodegradable until after an initial
thermal degradation. The temperatures in an industrial compost facility are hot enough to thermally
degrade PLA. After the thermal degradation, PLA will biodegrade and pass the test. This is the primary
reason that many plastics that are industrial compostable are not compostable in a back yard. In
backyard compost the temperature will almost never reach as high as an industrial compost
environment.
ASTM D6400 does not validate biodegradability for any environments outside of industrial composting,
including landfilling, littering, marine disposal or home composting. Some companies misrepresent
biodegradability testing, stating that the only test for biodegradability is ASTM D6400. However, ASTM
D6400 relates to industrial compostability; it does not confirm biodegradability in any other
environment.
ASTM D6400 is an appropriate protocol to use for plastics that will be placed into an industrial compost
facility after use.
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Part 6: Environmental Marketing of Plastics
As sustainability managers move their company into more sustainable materials and practices, there is a
desire to communicate this progression to consumers and the market in the form of marketing. A
successful company will build a sustainability platform that encompasses many aspects of the company
rather than focusing on a specific attribute of one product. In essence, they market a sustainable
company rather than a standard company trying to sell a sustainable product. Even with this approach,
companies may choose to highlight the features of a product through specific marketing.
Marketing, especially in the sustainability arena, should be accurate, clear and understandable to the
consumer. This will involve understanding the information presented in previous chapters, including
where the plastic will go after use. Meaning, the marketing should relate to where the plastic will
actually be disposed.
Marketing claims should always include the customary disposal environment of the product or
packaging. This is not always the same as the optimal disposal. A company may produce a product or
packaging that they want to be recycled, but if it is most likely to be disposed of in a landfill than the
marketing must reflect the landfill disposal.
For example: a plastic fork is going to be in a stadium where all utensils are collected with food waste
and sent to a compost; claims of recyclability should not be made – even when it is made from a plastic
that is technically recyclable. Likewise, a fork made from a compostable plastic when sold in an
environment where it will be disposed of in a landfill, should not have a claim of compostability.
While the details of how to appropriately market specific aspects of sustainability may vary, the overall
theme remains the same; keep your marketing message easily understood and accurate. Validation for
specific claims of performance requires reliable scientific evidence. If your marketing claim could easily
be misinterpreted, provide enough clarification to avoid misinterpretation of the claim.
This clarification is considered a “qualification” and it makes the difference between a qualified claim
and an unqualified claim. Unqualified claims are often scrutinized because they can be confusing and
misleading. Qualified claims clearly state enough detail about the claim to specify the specific attribute
and benefit you are marketing.
An example of an unqualified claim vs. qualified claim would be:
A plastic trash bag made of plastic that has been tested using ASTM D5526 with results of 61%
biodegradation in 205 days during that test.


An unqualified claim would be to simply label the bag as “Biodegradable”.
A qualified claim would label the bag as “Landfill Biodegradable*” and include the qualifying
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statement “*ASTM D5526 testing showed up to 61% biodegradation within 205 days”
The qualifying statement provides additional information to clarify the customary disposal environment
where the bags will biodegrade and what biodegradation performance could be expected. You will
notice that the qualifier does not interpret the test results or make claims beyond the scientific
validation.
Additionally, a marketing claim should be applicable to the real world scenario, meaning that a claim
should be based on the current processes and technologies used in handling of discarded materials. This
will ensure that the benefit claimed in marketing will actually be achieved.
For example: A plastic bag made of HDPE. HDPE is one of the two common recycled plastics. A bag
marketed as recyclable would be misleading because most recycling facilities do not regularly accept
HDPE in a bag form. So while the bag is made out of a recyclable plastic, it is not a recyclable product
because there are no readily available recycling facilities that accept and process HDPE bags. A claim of
recyclability would mislead consumers and the public into believing that there is an environmental
benefit to the bag in the form of recyclability, when in fact there is not.
The primary focus with marketing is to showcase beneficial attributes of your product. Your marketing
should clearly convey what those attributes are without overstating the environmental benefit.
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Section 1: General Environmental Claims
General marketing claims of environmental benefit are phrases such as; green, earth friendly or
sustainable. These types of claims are very broad and give the impression of a wide scope
environmental benefit, and imply that all the aspects of the product are beneficial for the environment.
These types of claims can be used, but should always have a qualifying statement to clarify why your
product is more beneficial. The qualifying statement should clearly identify what specific environmental
benefit your product provides and that you have the reliable scientific validation to back up the claim.
The US Federal Trade Commission’s 2013 Updated Green Guides state, “not to make unqualified general
environmental benefit claims because ‘‘it is highly unlikely that marketers can substantiate all
reasonable interpretations of these claims.’’ The Guides further provide that marketers may be able to
qualify general environmental benefit claims to focus consumers on the specific environmental benefits
that they can substantiate. In doing so, marketers should use clear and prominent qualifying language to
convey that a general environmental claim refers only to a specific and limited environmental
benefit(s).” (Register, 2012)
So, it is OK to use general claims as part of your overall marketing, just be sure to provide enough
information (qualifiers) to explain what you mean by the general term and why your product applies.
Example: The term ‘‘Eco-friendly’’ likely conveys that the product has far reaching environmental
benefits and may convey that the product has no negative environmental impact. However, simply
adding a qualifying statement such as; ‘‘Eco-friendly: made with recycled materials,’’ better clarifies how
your product is more environmentally beneficial.
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Section 2: Degradable and Biodegradable Claims
Degradable claims refer to the breakdown or decomposition of a material. As with the other types of
environmental marketing claims, degradable claims should also be qualified, to clarify what type of
degradation, where it will degrade and the performance a consumer should expect. The claim should
also be relevant to the actual disposal environment of the product.
Degradable claims cover a fairly wide spectrum of environments and material performances, so
degradable claims should indicate what type of degradation is going to occur, and if it is not
biodegradation, clarify what it will degrade into.
As with other claims, there must be valid scientific evidence that the plastic degradation will perform as
claimed. The evidence must be relevant to the environment where the plastic will be disposed.
The US Federal Trade Commission’s Updated Green Guides state, “A marketer should qualify a
degradable claim unless it has competent and reliable scientific evidence that the ‘‘entire product or
package will completely break down and return to nature, i.e., decompose into elements found in
nature within a reasonably short period of time after customary disposal.’’ (Register, 2012)
Note: The US FTC Green Guides state that a “reasonably short period of time” is one
year, however more recently an FTC court ruling determined that claims of
biodegradability within a landfill do not need to prove complete biodegradability within
one year, biodegradable does not mean complete breakdown into elements found in
nature within one year after customary disposal, biodegradable refers to a biological
process by which microorganisms such as bacterial and fungi use the carbon found in
organic materials as a food source and that scientific literature defining biodegradation
does not require completion or impose a time frame. Additionally, consumers
understand that biodegradation rates vary depending on the materials and
environment, and it is not always a rapid process. (ECM Biofilms Inc, 2015)
Marketing a degradable product is done accurately by simply identifying the type of breakdown,
environment in which it will degrade and what rate of degradation can be expected. It is always
beneficial to qualify your degradable claim to avoid misinterpretation. And, don’t claim degradable or
biodegradable if your product will most likely be disposed of in an environment where the degradation
will not occur.
Example 1: A marketer advertises its trash bags using a ‘‘degradable’’ claim. The marketer relies on soil
burial tests to show that the product will decompose in the presence of water and oxygen. Consumers,
however, place trash bags into the garbage which goes to landfills or incinerators where they will not
degrade. This is a marketing claim that should not be made because the trash bags are expected to go
into an environment where the degradation will not take place.
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Example 2: A marketer advertises a commercial agricultural plastic mulch film with the claim
“photodegradable,’’ and qualifies the term with the phrase ‘‘Will break down into small pieces if left
uncovered in sunlight.’’ The advertiser possesses scientific evidence that product will break down, after
being exposed to sunlight, into sufficiently small pieces to become part of the soil. This is a correct claim
because it explains what type of degradation, what material is left after the degradation and identifies
an environment where the film is expected to be used.
Example 3: A plastic package marketed as landfill biodegradable, has scientific validation that the plastic
package will biodegrade in a landfill. The validation includes ASTM D5526 testing in which the plastic
biodegrades 61% in 202 days. The claim should be qualified with a statement clarifying the
biodegradation performance expected, such as “testing shows 61% biodegradation in 202 days”.
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Section 3: Recyclable Claims
Marketing claims of recyclability should be limited to products that are reasonably expected to be
recycled. A reasonable expectation means that recycling facilities that accept the product are available
to a substantial majority of consumers or communities where the product is sold or disposed of. A
product or package marketed as recyclable should be one that is collected, separated, or otherwise
recovered from the waste stream through an established recycling program for reuse or use in
manufacturing or assembling another item.
Manufacturers and brands should not label a product or packaging as recyclable simply because it
utilizes a certain resin identification code (plastic numbers 1-6). These marketing claims have no
substantiation on the environment the product will be placed in and misleading to the consumers who
believe that recyclable claims mean a product will be remanufactured into a new product if it is placed
in the recycle stream. Recyclable claims must be based on the fact that the only items recycled at any
significant percentage are PET and HDPE bottles.
The recyclability of a package or product will change over time as recycling technologies improve. Today,
recycling on a mass scale is limited to PET beverage bottles and HDPE rigid containers. Other products
should not be marketed as recyclable unless the community where the product is sold or discarded has
programs that recycle that specific application. Qualifications can clarify to the consumer that the
recycling may not be available in their area by stating: ‘‘this product [package] may not be recyclable in
your area,’’ or ‘‘this product [package] is recyclable only in the few communities that have appropriate
recycling facilities.’’
Certain phrases or images can also be a claim of recyclability without directly stating “recyclable”. If a
product has labeling that states “Please Recycle” this would imply that the product is recyclable, if it is
not a material and in a form that is readily accepted by recycling facilities, the claim would be
misleading. The same situation will occur if the product has a prominent marking showing a triangle with
chasing arrows, as consumers interpret this as meaning recyclable.
The US Federal Trade Commission’s 2013 Updated Green Guides state, “Marketers can make unqualified
recyclable claims for a product or package if the entire product or package, excluding minor incidental
components, is recyclable. For items that are partially made of recyclable components, marketers
should clearly and prominently qualify the recyclable claim to avoid deception about which portions are
recyclable. If any component significantly limits the ability to recycle the item, any recyclable claim
would be deceptive. An item that is made from recyclable material, but, because of its shape, size, or
some other attribute, is not accepted in recycling programs, should not be marketed as recyclable.”
(Register, 2012)
Example 1: A multi-layer carton made of plastic, paper and metal foil is marketed as recyclable. The
majority of recycling facilities do not have the means to separate the layers or recycle the carton. This
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product should not have a claim of recyclability.
Example 2: A frozen food product packaged in an HDPE plastic film. While HDPE is recycled when it is in
the form of rigid containers, it is not readily recycled in films as used for this product. This product
should not have a claim of recyclability. It is also likely that this plastic film includes layers of other types
of plastic to increase the shelf life of the frozen food. Multi-layer film should not be labeled as
recyclable.
Example 3: A beverage bottle made of PET and the cap and label made of other materials that are easily
separated from the plastic bottle during the recycling process. Even though the majority of the PET
bottles are not collected for recycling, the majority of consumers have access to recycling programs that
regularly accept PET bottles. This is a product that can be accurately marketed as recyclable.
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Section 4: Compostable Claims
Marketing claims of compostability should also be qualified to clarify if it is home compostable,
industrial compostable and if there are appropriate composting facilities that will accept the product
readily available to the consumer after use. Before you market a product as compostable; make sure
you have solid scientific validation that it will in fact compost in the environment where it is likely to be
disposed.
For clarification, a plastic product may pass testing criteria for composting, meaning the plastic is
technically compostable. If there is rarely the chance that the product will be disposed of in an
environment where it will compost, then a claim of compostability is misleading because consumers will
believe there is an environmental value with the product when there is not.
The US Federal Trade Commission’s 2013 Updated Green Guides state, “that marketers should possess
competent and reliable scientific evidence showing that ‘‘all the materials in the product or package will
break down into, or otherwise become a part of, usable compost (e.g., soil conditioning material, mulch)
‘‘in approximately the same time as the materials with which it is composted in an appropriate
composting program or facility, or in a home compost pile or device.’’ (Register, 2012)
Marketing of compostable plastics is fairly easy if the claim includes qualifying statements regarding
what type of compost facility is required (home or industrial) and if there are appropriate facilities in the
area where it will be disposed. Don’t put compostable claims on products that will not reasonably be
placed in compost operations.
Example 1: A manufacturer indicates that its unbleached coffee filter is compostable. The unqualified
claim is not deceptive, provided the manufacturer has substantiation that the filter can be converted
safely to usable compost in a timely manner in a home compost pile or device. If so, the extent of local
municipal or institutional composting facilities is irrelevant.
Example 2: A manufacturer makes a claim that its package is compostable. Although municipal or
institutional composting facilities exist where the product is sold, the package will not break down into
usable compost in a home compost pile or device. To avoid deception, the manufacturer should clearly
and prominently disclose that the package is not suitable for home composting.
Example 3: Nationally marketed lawn and leaf bags state ‘‘compostable’’ on each bag. The bags also
feature text disclosing that the bag is not designed for use in home compost piles. Yard trimmings
programs in many communities compost these bags, but such programs are not available to a
substantial majority of consumers or communities where the bag is sold. The marketer should clearly
and prominently indicate the limited availability of such programs. A marketer could state ‘‘Appropriate
facilities may not exist in your area,’’ or provide the approximate percentage of communities or
consumers for which such programs are available.
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Example 4: A trash bag is marketed as “compostable”. Consumers, however, place trash bags into the
garbage which goes to landfills or incinerators where they will not compost. This is a marketing claim
that should not be made because the trash bags are expected to go into an environment where the
composting will not take place.
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Part 7: A Sustainable Approach to Plastic Waste
If we are to ever achieve true sustainability as a human race we must change our way of thinking and
acting. Albert Einstein once said, “No problem can be solved by the same kind of thinking that created
it.” Historically sustainability has been driven largely by cost savings, marketability to consumers, media
trends and social pressures. In essence, sustainability has not been focused on a company becoming
more sustainable, rather sustainability has been a smokescreen to make business as usual appear to
have changed when instead the primary objective still remains a commercial one.
A company that is genuinely focused on sustainability will know that it is not about reducing negative
impacts, sustainability is about creating positive impacts; environmentally, socially and economically. A
sustainable company will make decisions based on what is right rather than what is popular or trendy.
They will accept that cost is simply a matter of perception and understand that cost analysis must
extend beyond a simple financial assessment so that any increased financial costs can be offset by a
reduction of environmental or social costs. A sustainable company will make decisions based on facts
and data and use marketing as a method to educate their customers rather than sensationalize promises
that hold no merit.
A sustainable society is built by sustainable industries and sustainable industries are built one
sustainable company at a time. As more companies admit there is a better way to be in business and
integrate sustainability in all their decisions, it will put pressure on their competitors to do the same.
These industry leaders will drive innovation and change; they will stand as beacons to their industry and
as such will ensure their longevity and growth. Consumers will know who these leaders are, not by their
marketing schemes, but by who and what they stand for, how they operate and the integrity apparent
through the decisions they make. These companies know that sustainability is not only good for
business, sustainability is critical for the survival of business.
Sustainability comes in many forms; financial, environmental and social. This document has touched on
each of these aspects as it relates to plastics. Some feel that plastics cannot be part of a sustainable
society while they turn a blind eye to the value plastics brings to modern life and the impact of the
materials it has replaced. Plastics are a critical part of modern life; they provide protection for products,
prevent food spoilage and contamination, are an inexpensive material for the manufacturing of
products, are very durable and are extremely versatile.
Even so, plastics can create harm to our environment because they linger for hundreds or thousands of
years. When considering the sustainability as it relates to plastic, the primary concern is most often the
disposal of plastic after use. This is primarily because the media sensationalizes negative issues
regarding the use and disposal of plastics.
There are currently several different ways plastics can be disposed after use; landfilling, recycling,
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incineration and composting. Which of these options is best for a specific product will depend primarily
on the disposal available to the consumer. If there are several options readily available, then a
sustainability manager can design products and packaging specific to the disposal option of their
choosing. In considering the disposal method, it is important to understand that landfilling is by far the
most available and common method of disposal for plastic, so landfilling must always be addressed in
product design.
A full evaluation of the disposal options and the varying types of materials brings a solid conclusion:
there is not one single option that is the most beneficial for all types of plastics in all regions. However,
we can identify a strategy for varied waste management that includes each disposal method and
correlates the best materials with that process.
Sustainability managers must first and foremost understand that over 90% of plastics are deposited into
landfills. Even plastics with higher recycling rates such as PET beverage bottles and HDPE bottles have a
higher percentage entering the landfill than being recycled. This means that every sustainability decision
must provide a beneficial aspect regarding the landfilling of that plastic.
The most beneficial option for landfilled plastics is biodegradation and conversion of the resulting
methane to energy. Biodegradation will ensure the plastic does not linger for thousands of years by
converting the plastic back to natural materials, soil, air (carbon dioxide and methane), and water. When
the biodegradation is completed during the managed life of a landfill (2-50 years) the methane
produced is captured and used as energy and fuel.
Traditional plastics can biodegrade in landfills through the use of technologies such as ENSO RESTORE.
This technology maintains the physical properties of the plastic so that products and packaging remain
durable during use and then once the plastic enters the landfill it biodegrades during the managed life of
that landfill. This technology is available today and at very little cost.
Using technologies such as ENSO RESTORE allow the continued use of traditional plastics while
integrating biodegradability into our current landfill infrastructure so the energy value of the plastic can
be captured and the plastic will return to a natural form. In short, the plastic is already going to the
landfill and the landfill is already collecting the gas so the only change required is a simple adjustment to
the plastic itself. Sustainability managers should implement landfill biodegradability for all their plastic
products and packaging that will likely be placed in a landfill after use.
While this approach may seem contrary to the public perception of “zero waste”, it is in fact part of the
same directive. By utilizing technologies, such as ENSO RESTORE, to achieve controlled biodegradation it
is possible to achieve zero waste through full biodegradation. This complete biodegradation integrates
in the natural carbon cycle while also creating clean energy to offset fossil fuel use. Interestingly, the
energy consumed in collection is at least 60% less than the energy generated by the recovery and use of
the landfill gas (LFG) (Caraban, 2008) indicating that LFG energy can not only offset the energy
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requirements in waste collection but in single source collection can be a net positive.
LFG is a critical part of the overall energy profile for municipalities as LFG is a local, renewable energy
resource. Because landfill gas is generated continuously, it provides a reliable fuel for a range of energy
applications, including power generation and direct use. (EPA, A Landfill Gas To Energy Project
Development Handbook) Landfill gas is one of the few renewable energy resources that, when used,
actually removes pollution from the air.
Once landfilling of plastic is addressed, other disposal options can be considered as well. Depending on
the product or packaging involved, recycling may be an important focus. Too often it is assumed that
recycling is always beneficial. Studies show that while recycling of some plastics can have a beneficial
footprint; the resources required for collecting and processing the majority of mixed plastics for
recycling purposes negates any benefit. We also cannot put our heads in the sand and pretend that our
products and packaging are sustainable because they are “recyclable” when that plastic has little if any
chance to actually be recycled.
Sustainability managers that want to incorporate recycling as part of their overall strategy will design
their products and packaging to integrate effectively with current recycling processes. This will entail
converting all plastics to clear PET or HDPE bottles. They will avoid adding any labels or caps that are not
easily removed and they will not use multi-layering of plastics in their bottles. Products and packaging
that are not PET bottles or HDPE bottles do not have readily available recycling facilities and will most
likely not be recycled. It is misleading for a company to make any claims of recyclability for products and
packaging that are anything other than PET beverage bottles and HDPE bottles.
For many products, packaging in bottles may not be possible and changing a product or packaging based
solely on the ability to recycle the item will have unintended consequences. Sustainability managers
must balance the cost and performance of their plastic with the disposal environment they intend for
their products. Not all packaging performs as needed when it is the type and form of plastic most
recycled; for these products, designing for alternative disposal methods is appropriate.
Sustainability managers must avoid misleading the public by claiming a plastic package or product is
recyclable when it is in a form that is not recycled. There are many items that may be manufactured out
of PET or HDPE but will not be recycled due to their form or intended use (items smaller than a beverage
bottle, made out of multiple types of materials, foamed plastic and plastic films). Claiming that these
products are recyclable is deceitful and damages public trust in companies.
The current attempt at increasing recycling by adding additional types of plastics into the system is
ineffective. The primary focus for recycling should be to increase the collection of both PET and HDPE
bottles. Current collection of these two items is less than 40% so there is significant room for doubling
these recycle rates with minimal impact to current processes. Other materials should be evaluated
carefully for full economic and environmental impact before implementing recycling as an option.
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Another option for plastics disposal is through industrial composting. The plastics that will provide the
most benefit in industrial compost are more limited than those that benefit through recycling. This is
because there is limited availability of industrial compost facilities that will accept plastics, there are few
plastics that will break down effectively in industrial compost and it is ineffective to try and sort plastics
and then send them to industrial composting facilities.
Sustainability managers that have products and packaging sold and disposed of in regions with generally
available industrial compost collection may want to consider compostability for select items such as;
food service items and bags used to contain the food waste. Composting these plastics will avoid the
energy and resources that would otherwise be required to sort these plastics from the food waste.
There is also value in the bags containing the food waste in human health aspects, odor control and
insect/animal avoidance. Additionally, the bags can prevent excess water use and water pollution that
would otherwise be produced when cleaning re-useable food waste containers.
Compostable plastics should only be used when the product is most likely to be disposed of in an
appropriate composting facility. This means that there must be widespread availability of commercial
compost collection where the product will be sold and disposed of. The plastic must also be in a form
and purpose that would make it commonly comingled with food or yard waste that will be going to an
industrial compost facility. Without availability of compost facilities and the expectation that the plastic
will most likely be disposed of in industrial compost there is no value in compostable plastics.
Note: Cost is sometimes a driving factor even when the primary focus is environmental.
Companies can overlook the fact that sustainability will always have a cost, you pay
whether you move into sustainability and you pay if you don’t. Ultimately, it is a matter
of when and how that cost is paid; we can pay it now by implementing sustainable
solutions, or we pay it later by trying to reverse environmental damage and damage to a
company’s reputation. Companies that successfully implement sustainable changes
understand that the financial cost of a change is offset by the social value and customer
loyalty that it provides. They understand that sustainability is a way of ensuring that
their company will continue in operation for many years to come.
Retailers often push against price increases stating that consumers are unwilling to pay
more for environmental products. Studies show that most consumers are willing to pay
up to 10% higher costs for green items. Also, prices fluctuate regularly and consumers
continue to purchase these items. Most consumers do not recognize small increases in
pricing unless the product with the increased cost is sold alongside a product that does
not have an increase in price.
Overall, sustainability with plastics is fairly simple. First, sustainability managers must acknowledge their
plastics will most likely be disposed of in a landfill. Armed with this information, sustainability managers
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can then implement solutions that ensure the plastic in the landfill will biodegrade effectively during the
managed life of the landfill. In this way the vast majority of their plastic products and packaging will
have a more sustainable end of life. Landfilling is addressed first and foremost because even plastics
that can be recycled or composted will most likely be disposed of into landfills.
Landfill biodegradable materials also provide a unique opportunity for brands and manufacturers
looking to improve their sustainability profile. Most often once a material leaves the factory there is no
method for the producer to control the disposal or end of life scenario of that product. Utilizing landfill
biodegradable materials is one of the few methods available that address the sustainability of materials
in the customary disposal method; creating a means for companies to implement extended producer
responsibility by ensuring that the end of life scenario is beneficial even when the producer no longer
has possession of the product.
After a company has made sure their plastic products and packaging are biodegradable within the
landfill, then alternative methods of disposal can be evaluated. Recycling and composting can be
evaluated to determine any possible benefit of designing products and packaging to integrate into these
alternative methods. This evaluation will use facts and data to determine if the plastic will perform as
expected during recycling or composting, if the plastic has a high chance of being recycled or composted
and if it is more beneficial to recycle or compost the plastic than to have it biodegrade in the landfill.
Using a systematic approach that first addresses the vast majority of the plastics will provide a wider and
more immediate impact – basically more bang for the buck. Too often, sustainability managers focus on
areas that are sensationalized by the media and have great marketability but prove very little true
impact. Rather than implementing solutions for the 90%, the focus of many sustainability managers has
in the past wasted time, energy and effort trying to save a small fraction of their plastics.
In conclusion, the message is simple: Understand where your plastics will be disposed of, implement
solutions based on this environment and use your marketing to educate the public. Don’t worry about
the 10% of plastic until you have solved the 90% in the landfill. Don’t use clever marketing tactics that
mislead the public regarding the true end of life scenario for your plastic product and packaging. And
don’t be afraid to do the right thing, even when it is unpopular because we cannot solve this problem
with the same type of thinking that created the problem.
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About the Author:
Teresa Clark is the VP of Product Development with ENSO Plastics, LLC, where she develops sustainable
solutions for the materials industry. One key focus is the development of technologies that accelerate
the natural bio-remediation of materials in the waste environment. It is on this subject that she created
and instructed a continuing education course for the PR College of Engineers, and developed an
educational program for middle school children to educate them on plastics, biodegradation and the
environment which has been used in several private schools. Teresa also is a member of ASTM
International within several technical sub-committees including; Rubber, Bio-technology, Waste
Management, Bio-Technology, Packaging and Sustainability. She also is the Vice-Chair of Arizona
Businesses Advancing Sustainability (AZBAS) where she oversees the development and implementation
of sustainable strategies and educational outreach. Teresa is an avid environmentalist with experience
in microbiology, chemistry, biodegradation and related environmental fields and holds a passion for
sharing her knowledge with the industry. She has been a featured educational speaker at multiple
conferences in the plastics, waste management and rubber industries as well as published research
papers on biodegradation.
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